THE  LIBRARY 

OF 

THE  UNIVERSITY 
OF  CALIFORNIA 

GIFT  OF 

Professor 
Charles  M.  Gilbert 


THE 

ANCIENT    LIFE-HISTORY 


OF 


THE     EARTH 


THE 


ANCIENT     LIFE-HISTORY 


OF 


THE     EARTH 


A  COMPREHENSIVE  OUTLINE  OF  THE    PRINCIPLES 

AND   LEADING   FACTS   OF   PAL^ON- 

TOLOGICAL  SCIENCE 


BY 


II.    ALLEYNE  ^ICHOLSON 

M.D.,  D.Sc.,  M.A.,  PH.D.  (GoTT.),  F.R.S.E.,  F.L.S. 

PROFESSOR    OF    NATURAL    HISTORY    IN   THE 
UNIVERSITY  OF   ST    ANDREWS 


NEW    YORK: 
D.    APPLETON    AND    COMPANY, 

72     FIFTH     AVENUE. 
1895. 


'r 

Add«l 

GIFT 


RTH 

SCIENCES 
UBBAfiY 


PREFACE. 


TlIE  study  of  Palaeontology,  or  the  science  which  is 
concerned  with  the  living  beings  which  flourished  upon 
the  globe  during  past  periods  of  its  history,  may  be 
pursued  by  two  parallel  but  essentially  distinct  paths. 
By  the  one  method  of  inquiry,  we  may  study  the 
anatomical  characters  and  structure  of  the  innumerable 
extinct  forms  of  life  which  lie  buried  in  the  rocks 
simply  as  so  many  organisms,  with  but  a  slight  and 
secondary  reference  to  the  time  at  which  they  lived. 
By  the  other  method,  fossil  animals  are  regarded  prin- 
cipally as  so  many  landmarks  in  the  ancient  records  of 
the  world,  and  are  studied  historically  and  as  regards 
their  relations  to  the  chronological  succession  of  the 
strata  in  which  they  are  entombed.  In  so  doing,  it  is 
of  course  impossible  to  wholly  ignore  their  structural 
characters,  and  their  relationships  with  animals  now 
living  upon  the  earth  ;  but  these  points  are  held  to 
occupy  a  subordinate  place,  and  to  require  nothing 
more  than  a  comparatively  general  attention. 

In  a  former  work,  the   Author  has  endeavoured   to 
furnish    a    summary    of   the    more    important    facts    of 

M878175 


VI  PREFACE. 

Palaeontology  regarded  in  its  strictly  scientific  aspect, 
as  a  mere  department  of  the  great  science  of  Biology. 
The  present  work,  on  the  other  hand,  is  an  attempt  to 
treat  Palaeontology  more  especially  from  its  historical 
side,  and  in  its  more  intimate  relations  with  Geology. 
In  accordance  with  this  object,  the  introductory  portion 
of  the  work  is  devoted  to  a  consideration  of  the  general 
principles  of  Palaeontology,  and  the  bearings  of  this 
science  upon  various  geological  problems — such  as  the 
mode  of  formation  of  the  sedimentary  rocks,  the  reac- 
tions of  living  beings  upon  the  crust  of  the  earth,  and 
the  sequence  in  time  of  the  fossiliferous  formations. 
The  second  portion  of  the  work  deals  exclusively  with 
Historical  Palaeontology,  each  formation  being  consid- 
ered separately,  as  regards  its  lithological  nature  and 
subdivisions,  its  relations  to  other  formations,  its  geo- 
graphical distribution,  its  mode  of  origin,  and  its  char- 
acteristic life-forms. 

In  the  consideration  of  the  characteristic  fossils  of 
each  successive  period,  a  general  account  is  given  of 
their  more  important  zoological  characters  and  their 
relations  to  living  forms ;  but  the  technical  language  of 
Zoology  has  been  avoided,  and  the  aid  of  illustrations 
has  been  freely  called  into  use.  It  may  therefore  be 
hoped  that  the  work  may  be  found  to  be  available  for 
the  purposes  of  both  the  Geological  and  the  Zoological 
student  ;  since  it  is  essentially  an  outline  of  Historical 
Palaeontology,  and  the  student  of  either  of  the  above- 
mentioned  sciences  must  perforce  possess  some  know- 
ledge of  the  last.  Whilst  primarily  intended  for  stu- 
dents, it  may  be  added  that  the  method  of  treatment 
adopted  has  been  so  far  untechnical  as  not  to  render 
the  work  useless  to  the  general  reader  who  may  desire 


PREFACE.  Vil 

to  acquire  some  knowledge  of  a  subject  of  such  vast 
and  universal  interest. 

In  carrying  out  the  object  which  he  has  held  before 
him,  the  Author  can  hardly  expect,  from  the  nature  of 
the  materials  with  which  he  has  had  to  deal,  that  he  has 
kept  himself  absolutely  clear  of  errors,  both  of  omission 
and  commission.  The  subject,  however,  is  one  to  which 
he  has  devoted  the  labour  of  many  years,  both  in 
studying  the  researches  of  others  and  in  personal 
investigations  of  his  own;  and  he  can  only  trust  that 
£uch  errors  as  may  exist  will  be  found  to  belong  chiefly 
to  the  former  class,  and  to  be  neither  serious  nor 
numerous.  It  need  only  be  added  that  the  work  is 
necessarily  very  limited  in  its  scope,  and  that  the 
necessity  of  not  assuming  a  thorough  previous  acquaint- 
ance with  Natural  History  in  the  reader  has  inexorably 
restricted  its  range  still  further.  The  Author  does  not, 
therefore,  profess  to  have  given  more  than  a  merely 
general  outline  of  the  subject ;  and  those  who  desire 
to  obtain  a  more  minute  and  detailed  knowledge  of 
Palaeontology,  must  have  recourse  to  other  and  more 
elaborate  treatises. 


UNITED  COLLEGE,  ST  ANDREWS. 
October  2,  1876. 


CONTENTS. 


PART     I. 
PRINCIPLES   OF   PALAEONTOLOGY. 


INTRODUCTION. 

PAGE 

The  general  objects  of  geological  science— The  older  theories  of 
catastrophistic  and  intermittent  action — The  more  modern  doc- 
trines of  continuous  and  uniform  action — Bearing  of  these  doc- 
trines respectively  on  the  origin  of  the  existing  terrestrial  order — 
Elements  of  truth  in  Catastrophism — General  truth  of  the  doc- 
trine of  Continuity — Geological  time,  ....  i-io 

CHAPTER   I. 

Definition  of  Palaeontology — Nature  of  Fossils — Different  processes 

of  fossilisation, 10-14 


CHAPTER   II. 

Aqueous  and  igneous  rocks — General  characters  of  the  sedimentary 
rocks — Mode  of  formation  of  the  sedimentary  rocks — Definition 
of  the  term  "formation  " — Chief  divisions  of  the  aqueous  rocks 
— Mechanically-formed  rocks,  their  characters  and  mode  of  origin 
— Chemically  and  organically  f&rmed  rocks — Calcareous  rocks — 
Chalk,  its  microscopic  structure  and  mode  of  formation — Lime- 
stone, varieties,  structure,  and  origin — Phosphate  of  lime — Con- 
cretions— Sulphate  of  lime — Silica  and  siliceous  deposits  of  vari- 
ous kinds — Greensands— Red  clays — Carbon  and  carbonaceous 
deposits, 14-36 


CHAPTER   III. 

Chronological  succession  of  the  fossiliferous  rocks — Tests  of  age  of 
strata — Value  of  Palseontological  evidence  in  stratigraphical  Geo- 
logy— Gene'ral  sequence  of  the  great  formations,  .  .  37-44 


CONTENTS. 


CHAPTER    IV. 

The  breaks  in  the  palaeontological  and  geological  record — Use  of 
the  term  "contemporaneous"  as  applied  to  groups  of  strata — 
General  sequence  of  strata  and  of  life-forms  interfered  with  by 
more  or  less  extensive  gaps  — Unconformability — Phenomena  im- 
plied by  this— Causes  of  the  imperfection  of  the  paloeontological 
record, 44'52 

CHAPTER  V. 

Conclusions  to  be  drawn  from  fossils — Age  of  rocks — Mode  of  origin 
of  any  fossiliferous  bed — Fluviatile,  lacustrine,  and  marine  de- 
posits— Conclusions  as  to  climate — Proofs  of  elevation  and  subsi- 
dence of  portions  of  the  earth's  crust  derived  from  fossils,  .  52-56 

CHAPTER  VI. 

The  biological  relations  of  fossils — Extinction  of  life-forms — Geolo- 
gical range  of  different  species — Persistent  types  of  life — Modern 
origin  of  existing  animals  and  plants — Reference  of  fossil  forms 
to  the  existing  primary  divisions  of  the  animal  kingdom — Depart- 
ure of  the  older  types  of  life  from  those  now  in  existence — Re- 
semblance of  the  fossils  of  a  given  formation  to  those  of  the  for- 
mation next  above  and  next  below — Introduction  of  new  life- 
forms,  «  ,  ,  57-6l 


PART     II. 
HISTORICAL   PALAEONTOLOGY. 

CHAPTER  VII. 

The  Laurentian  and  Huronian  periods — General  nature,  divisions, 
and  geographical  distribution  of  the  Laurentian  deposits — Lower 
and  Upper  Laurentian — Reasons  for  believing  that  the  Lauren- 
tian rocks  are  not  azoic  based  upon  their  containing  limestones, 
beds  of  oxide  of  iron,  and  graphite — The  characters,  chemical 
composition,  and  minute  structure  of  Eozoon  Canadense—  Compar- 
ison of  Eozoon  with  existing  Foraminifera — Archceospharince — 
Huronian  formation — Nature  and  distribution  of  Huronian  de- 
posits—Organic  remains  of  the  Huronian — Literature,  •  65-76 

CHAPTER   VIII. 

The  Cambrian  period— General  succession  of  Cambrian  deposits  in 
Wales — Lower  Cambrian  and  Upper  Cambrian — Cambrian  de- 
posits of  the  continent  of  Europe  and  North  America — Life  of  the 
Cambrian  period  —  Fucoids — Eophyton — Oldhamia — Sponges — 
Echinoderms — Annelides — Crustaceans — Structure  of  Trilobites 
— Brachiopods — Pteropods,  Gasteropods,  and  Bivalves — Cephalo- 
pods— Literature,  .  .  .  .  .  .  .-  .  77-90 


CONTENTS.  xi 


CHAPTER    IX. 

The  Lower  Silurian  period — The  Silurian  rocks  general!/ — Limits  of 
Lower  and  Upper  Silurian — General  succession,  subdivisions,  and 
characters  of  the  Lower  Silurian  rocks  of  Wales — General  succes- 
sion, subdivisions,  and  characters  of  the  Lower  Silurian  rocks 
of  the  North  American  continent — Life  of  the  period — Fucoids — 
Protozoa — Graptolites — Structure  of  Graptolites — Corals — Gene- 
ral structure  of  Corals — Crinoids — Cystideans — General  characters 
of  Cystideans — Annelides — Crustaceans — Polyzoa — Brachiopods 
— Bivalve  and  Univalve  Molluscs — Chambered  Cephalopods — 
General  characters  of  the  Cephalopoda — Conodonts,  .  .  90-114 


CHAPTER  X. 

The  Upper  Silurian  period — General  succession  of  the  Upper  Silurian 
deposits  of  Wales — Upper  Silurian  deposits  of  North  America — 
Life  of  the  Upper  Silurian — Plants  —  Protozoa — Graptolites — 
Corals — Crinoids — General  structure  of  Crinoids — Star-fishes — 
Annelides — Crustaceans — Eurypterids — Polyzoa — Brachiopods — 
Structure  of  Brachiopods— Bivalves  and  Univalves — Pteropods — 
Cephalopods — Fishes — Silurian  literature,  .  .  115-132 


CHAPTER   XI. 

The  Devonian  period'— Relations  between  the  Old  Red  Sandstone 
and  the  marine  Devonian  deposits — The  Old  Red  Sandstone  of 
Scotland — The  Devonian  strata  of  Devonshire — Sequence  and 
subdivisions  of  the  Devonian  deposits  of  North  America — Life  of 
the  period — Plants — Protozoa — Corals — Crinoids — Pentremites — 
Annelides — Crustaceans  —  Insects — Polyzoa — Brachiopods — Bi- 
valves —  Univalves — Pteropods — Cephalopods — Fishes — General 
divisions  of  the  Fishes — Palaeontological  evidence  as  to  the  inde- 
pendent existence  of  the  Devonian  system  as  a  distinct  formation 
— Literature,  .........  132-157 


CHAPTER   XII. 

The  Carboniferous  period— Relations  of  Carboniferous  rocks  to  De- 
vonian—  The  Carboniferous  Limestone  or  Sub  -  Carboniferous 
series — The  Millstone-grit  and  the  Coal-measures — Life  of  the 
period — Structure  and  mode  of  formation  of  Coal — Plants  of  the 
Coal, 157-170 


CHAPTER   XIII. 

Animal  life  of  the  Carboniferous  period — Protozoa—  Corals — Crinoids 
— Pentremites — Structure  of  Pentremites — Echinoids — Structure 
of  Echinoidea  —  Annelides  —  Crustacea  —  Insects — Arachnids — 
Myriapods— Polyzoa — Brachiopods — Bivalves  and  Univalves — 
Cephalopods  —  Fishes  —  Labyrinthodont  Amphibians  —  Litera- 
ture, ..........  170-192 


xii  CONTENTS. 


CHAPTER   XIV, 

The  Permian  period— General  succession,  characters,  and  mode  of 
formation  of  the  Permian  deposits — Life  of  the  period — Plants — 
Protozoa  —  Corals  —  Echinoderms  —  Annelides  —  Crustaceans — 
Polyzoa  —  Brachiopods  —  Bivalves  —  Univalves  —  Pteropods  — 
Cephalopods — Fishes — Amphibians — Reptiles — Literature,  192-203 

CHAPTER   XV. 

The  Triassic  period — General  characters  and  subdivisions  of  the  Trias 
of  the  Continent  of  Europe  and  Britain — Trias  of  North  America 
— Life  of  the  period— Plants — Echinoderms — Crustaceans — Poly- 
zoa— Brachiopods  —  Bivalves — Univalves —  Cephalopods — Inter- 
mixture of  Palaeozoic  with  Mesozoic  types  of  Molluscs — Fishes — 
Amphibians — Reptiles — Supposed  footprints  of  Birds  — Mammals 
— Literature, 203-225 


CHAPTER  XVI. 

The  Jurassic  period — General  sequence  and  subdivisions  of  the  Juras- 
sic deposits  in  Britain— Jurassic  rocks  of  North  America — Life 
of  the  period — Plants — Corals — Echinoderms — Crustaceans— In- 
sects —  Brachiopods  —  Bivalves  —  Univalves  —  Pteropods — Tetra- 
branchiate  Cephalopods — Dibranchiate  Cephalopods — Fishes — 
Reptiles — Birds — Mammals — Literature,  .  .  .  226-256 

CHAPTER  XVII. 

The  Cretaceous  period — General  succession  and  subdivisions  of  the 
Cretaceous  rocks  in  Britain — Cretaceous  rocks  of  North  America 
— Life  of  the  period— Plants — Protozoa — Corals — Echinoderms 
— Crustaceans  —  Polyzoa  —  Brachiopods — Bivalves — Univalves — 
Tetrabranchiate  and  Dibranchiate  Cephalopods — Fishes — Rep- 
tiles— Birds— Literature,  .  .  .  .  .  .  .  256-284 

CHAPTER    XVIII. 

The  Eocene  period — Relations  between  the  Kainozoic  and  Mesozoic 
rocks  in  Europe  and  in  North  America— Classification  of  the 
Tertiary  deposits — The  sequence  and  subdivisions  of  the  Eocene 
rocks  of  Britain  and  France — Eocene  strata  of  the  United  States 
— Life  of  the  period — Plants — Foraminifera—  Corals — Echino- 
derms— Mollusca — Fishes — Reptiles — Birds— Mammals,  .  284-305 

CHAPTER   XIX. 

The  Miocene  period — Miocene  strata  of  Britain— Of  France — Of 
Belgium — Of  Austria — Of  Switzerland — Of  Germany — Of  Greece 
—  Of  India — Of  North  America — Of  the  Arctic  regions — Life  of 
the  period — Vegetation  of  the  Miocene  period — Foraminifera — 
Corals— Echinoderms — Articulates—  Mollusca — Fishes — Amphi- 
bians— Reptiles — Mammals,  .  .  .  .  .  305-323 


CONTENTS.  Xlll 


CHAPTER   XX. 

The  Pliocene  period— Pliocene  deposits  of  Britain— Of  Europe— Of 
North  America— Life  of  the  period — Climate  of  the  period  as 
indicated  by  the  Invertebrate  animals — The  Pliocene  Mammalia 
—Literature  relating  to  the  Tertiary  deposits  and  their  fossils,  323-333 


CHAPTER   XXI. 

The  Post- Pliocene  period— Division  of  the  Quaternary  deposits  into 
Post-Pliocene  and  Recent — Relations  of  the  Post-Pliocene  de- 
posits of  the  northern  hemisphere  to  the  *'  Glacial  period " — 
Pre-Glacial  deposits — Glacial  deposits — Arctic  Mollusca  in  Gla- 
cial beds — Post-Glacial  deposits — Nature  and  mode  of  formation 
of  high-level  and  low-level  gravels — Nature  and  mode  of  forma- 
tion of  cavern-deposits — Kent's  Cavern — Post-Pliocene  deposits 
of  the  southern  hemisphere,  ......  334-344 


CHAPTER  XXII. 

Life  of  the  Post-Pliocene  period— Effect  of  the  coming  on  and  de- 
parture of  the  Glacial  period  upon  the  animals  inhabiting  the 
northern  hemisphere — Birds  of  the  Post-Pliocene — Mammalia  of 
the  Post-Pliocene — Climate  of  the  Post-Glacial  period  as  deduced 
from  the  Post-Glacial  Mammals — Occurrence  cf  the  bones  and 
implements  of  Man  in  Post-Pliocene  deposits  in  association  with 
the  remains  of  extinct  Mammalia — Literature  relating  to  the  Post- 
Pliocene  period, 344-366 


CHAPTER    XXIII. 

The  succession  of  life  upon  the  globe — Gradual  and  successive  intro- 
duction of  life-forms — What  is  meant  by  "  lower  "  and  "higher" 
groups  of  animals  and  plants — Succession  in  time  of  the  great 
groups  of  animals  in  the  main  corresponding  with  their  zoological 
order — Identical  phenomena  in  the  vegetable  kingdom — Persist- 
ent types  of  life — High  organisation  of  many  early  forms — Bear- 
ings of  Palaeontology  on  the  general  doctrine  of  Evolution,  367-374 

APPENDIX.— Tabular   view   of  the   chief  Divisions   of  the   Animal 

Kingdom, 375"378 

GLOSSARY, 379-395 

INDEX, 396-407 


LIST   OF   ILLUSTRATIONS. 


FIG. 
I. 
2. 

3- 
4- 
5- 

6. 
7- 


9- 
10. 


12. 


13- 


IS- 

1  6. 

17- 


PAGE 

Cast  of  Trigonia  longa,  .  12 
Microscopic  section  of  the 

wood  of  a  fossil  Conifer,  1 3 
Microscopic  section  of  the 

wood  of  the  Larch,  .  13 
Section  of  Carboniferous 

strata,  Kinghorn,  Fife,  1 6 
Diagram  illustrating  the 

•  formation   of  stratified 
deposits,      ...        17 

Microscopic  section  of  a 

calcareous  breccia,  .  19 

Microscopic  section  of 
White  Chalk,  .  .  22 

Organisms     in     Atlantic 

-  Ooze,  ...       23 
Crinoidal  marble,    .         .       24 
Piece  of  Nummulitic  lime- 
stone, Pyramids,  .        25 

Microscopic  section  of  Fo- 
raminiferal  limestone — 
Carboniferous,  Amer- 


FIG. 

1 8. 


19. 

20. 
21. 
22. 

23- 
24. 

25- 
26. 

27. 

28. 
29- 
30- 

3*; 

32- 
33- 
34- 


ica,     .     •    .     -    .         .27 

Microscopic  section  of 
Lower  Silurian  lime- 
stone, .  .  .27 

Microscopic  section  of 
oolitic  limestone,  Ju- 
rassic, .  .  -29 

Microscopic  section  of 
ooolitic  limestone,  Car- 
boniferous, .  .  30  35. 

Organisms  in   Barbadoes 

•  earth,  .         .         -33 
Organisms   in   Richmond  36. 

•  earth,       •    .         .         .       33      37. 
Ideal  section  of  the  crust  38. 

of  the  earth,          .          .       43      39. 


Unconformable    junction 

of  Chalk  and   Eocene 

rocks,  ...  49 
Erect  trunk  of  a  Sigillaria,  54 
Diagrammatic  section  of 

the  Laurentian  rocks,  66 
Microscopic  section  of 

Laurentian  limestone,  67 
Fragment  of  a  mass  of 

Eoztion  Canadense,  .  69 
Diagram  illustrating  the 

structure  of  Eozoon,  .  70 
Microscopic-  section  of 

Eozoon  Canadense,  .  71 
ATonionina  and  Gromia,  .  72 
Group  of  shells  of  living 

Foraminifera,  .  .  73 
Diagrammatic  section  of 

Cambrian  strata,  .  78 

Eophyton  Linneanum,  .  81 
Oldhauiia  antiqua,  .  82 

Scolithus  Canadensis,  .  83 
Group  of  Cambrian  Trilo- 

bites,  ...  85 

Group  of  characteristic 

Cambrian  fossils,  .  88 
Fragment  of  Dictyonema 

sociale,  ...  89 
Generalised  section  of  the 

Lower   Silurian    rocks 

of  Wales,  ...  94 
Generalised  section  of  the 

Lower    Silurian    rocks 

of  North  America,  .  9^ 
Licrophycus  Oltaivaensis,  97 
A stylospongia  flmmorsa,  .  98 
Stromatopora  rugosa,  .  99 
Dichograptus  octobrach  iatus ,  I  o  I 


XVI 


LIST   OF   ILLUSTRATIONS. 


40.  Didymograptus    divarica- 

tUSy  .... 

41.  Diplograptus  pristis, 

42.  Phyllograptus  typus, 

43.  Zaphrentis  Stokesi,  . 

44.  Strombodes  pentagonus,    . 

45.  Columnaria  alveolata, 

46.  Group  of  Cystideans, 

47.  Group  of  Lower  Silurian 

Crustaceans, 

48.  Ptilodictya  falcifonnis, 

49.  Ptilodictya  Schaffei'i, 

50.  Group  of  Lower  Silurian 

Brachiopods, 

51.  Group  of  Lower  Silurian 

Brachiopods, 

52.  Murchisonia  gj-acilis, 

53.  Belter ophon  argo,     . 

54.  Maclurea  crenulata, 

55.  Orthoceras  crebriseptum, 

56.  Restoration  of  Orthoceras, 

57.  Generalised  section  of  the 

Upper  Silurian  rocks, 

58.  Monograptus  priodon, 

59.  Halysites  catenularia  and 

H.  agglomerata,  . 

60.  Group  of  Upper  Silurian 

Star- fishes, 

61.  Protasier  Sedgwickii, 

62.  Group  of  Upper  Silurian 

Crinoids,     . 

63.  Planolites  vulgaris,  . 

64.  Group  of  Upper  Silurian 

Trilobites,  . 

65.  Pterygotus  Anglicus, 

66.  Group  of  Upper  Silurian 

Polyzoa, 

67.  Spirifera  hysterica,  . 

68.  Group  of  Upper  Silurian 

Brachiopods, 

69.  Group  of  Upper  Silurian 

Brachiopods, 

70.  Pentamerus  Knightii, 

71.  Cardiola    interrupta,     C. 

jibrosa,     and   Pterin&a 
subfalcata,    . 

72.  Group  of  Upper  Silurian 

Univalves, 

73.  Tentaculites  ornatiis, 

74.  Pteraspis  Banksii,     . 

75-    Onchus  tenuistriatus    and 
Thelodus,    . 

76.  Generalised  section  of  the 

Devonian      rocks       of 
North  America, 

77.  Psilophyton  princess, 


78. 

102 

79- 

IO2 

80. 

102 

81. 

IO4 

82. 

104 

83- 

84- 

io6 

85. 

86. 

107 

109 

87- 

109 

88. 

109 

89- 

1  10 

in 

90. 

in 

91. 

112 

92. 

113 

93- 

"3 

94- 

U7 

at 

119 

97. 

98. 

120 

99. 

121 

100. 

121 

101. 

102. 

.122 

I23 

.103. 

124 

104. 

125 

105. 

106. 

126 

126 

107. 

127 

127 

108. 

I2S 

109. 

no. 

in. 

128 

112. 

129 

114. 

129 

130 

I30 

"5- 

116. 

137 

117. 

138 

Prolotaxites  Logani,  .  139 
Strotnatopora  tuber culata,  140 
Cystiphyllum  vesicttlostim,  141 
Zaphrentis  cornicula,  .  141 
Heliophyllum  exigimm,  141 
Crepidophyllum  Archiaci,  142 
Pavosites  Gothlandica,  .  143 
Favosites  hemispkcerica,  143 
Spirorbis  omphalodes  and 

S.  Arkonensis,  .  .144 
Spirorbis  laxus  and  S. 

spinulifera,  .          .144 

Group  of  Devonian  Tri- 
lobites,       .         .  144 
Wing    of    Platephemera 

antiqna,  .  .  .145 
Clathropora  intertexta,  .  146 
Ceriopora  Hamiltonensis,  146 
Fenestella  magnified,  .  146 
Retepora  PhUlipsi,  .  146 

Fenestella  cribrosa,  .     146 

Spirifera  sculptilis,  .  147 
Spirifera  mucronata,  .  147 
Atrypa  reticularis,  .  148 
Strophomena  rhomboid' 

alts,  .  .  .  .148 
Platyceras  dumosum,  .  148 
Conularia  ornata,  .  149 

Clymenia  Sedgwickii,      .     149 
Group    of  Fishes    from 
the  Devonian  rocks  of 
North  America,  .      151 

Cephalaspis  Lyellii,  .  152 
Pterichlhys  cornutus,  .  153 
Polypterus  and  Osteolepis,  154 
Holoptychius  nobilissi- 

mus,   .         .         .         .154 
Generalised     section    of 
the  Carboniferous  rocks 
of  the  North  of  Eng- 
land, .         .         .         .161 
Odontopteris  Schlotheimii,     164 
Calamites  c  anna: for  mis,        165 
Lepidodendron  Sternbergii,   167 
Sigillaria  Gra'seri,  .      1 68 

Stigmaria  ficoides,  .      1 69 

Trigonocarpum  ovatum,       170 
Microscopic    section    of 
Foraminiferal  limestone 
— Carboniferous,  North 
America,     .         .         .172 
Fusulina  cylindrica,        .      172 
Group  of  Carboniferous 

Corals,         .         .         .174 
Platycrinus    tricontadac- 
tylus,  .         .         .         .175 


LIST   OF   ILLUSTRATIONS. 


XV11 


n8. 

P.  conoideus, 

1 19.  Archtfocidaris  ellipticus, 

1 20.  Spirorbis  Carbonarizis,   . 

121.  Prestivickia  rotundata,    . 

122.  Group  of  Carboniferous 

Crustaceans, 

123.  Cyclophthalmus  senior,    . 

1 24.  Xylobius  Sigillari<e, 

125.  Haplophlebium  Barnesi, 

126.  Group  of  Carboniferous 

Polyzoa, 

127.  Group  of  Carboniferous 

Brachiopoda, 

128.  Pupa  vetiista, 

129.  Goniatites  Jossce,    . 

1 30.  A  mblypterus  macroptei'us, 

131.  Cochliodus  contortus, 

132.  Anthracosaurus  Russelli, 

133.  Generalised    section    of 

the  Permian  rocks, 

134.  Walchia  piniformis, 

135.  Group  of  Permian  Bra- 

chiopods,    . 

136.  Area  antiqua, 

137.  Platysomus  gibbosus, 

1 38.  Protorosaurus  Speneri,    . 

1 39.  Generalised  section  of  the 

Triassic  rocks,     . 

140.  Zamia  spiralis, 

141.  Triassic     Conifers     and 

Cycads, 

142.  Encrinus  liliiformia, 

143.  Aspidura  loricata, 

144.  Group    of    Triassic    Bi- 

valves, 

145.  Ceratites  nodosus,   . 

146.  Tooth  of  Ceratodus  ser- 

ratus  and  C.  altus, 

147.  Ceratodus  Fosteri, 

148.  Footprints     of     Cheiro- 

therium, 

149.  Section  of  tooth  of  Laby- 

rinthodont, 

1 50.  Skull  otMastodonsaurus, 

151.  Skull  of  Rhynchosaurus, 

152.  Belodon,       Nothosaurus, 

Palceosaurus,  &c., 

153.  Placodus  gigas, 

1 54.  Skulls  of  Dicynodon  and 

Oudenodon, 

155.  Supposed    footprint    of 

Bird,    from   the    Trias 
of  Connecticut,   . 

156.  Lower  jaw   of   Droma- 

theri^tm  sylvestre, 
2 


176 

*:>/• 

177 

158. 

178 

159- 

179 

1  60. 

180 

161. 

181 

162. 

182 

163. 

182 

164. 

165. 

183 

1  66. 

185 

167. 

186 

1  68. 

187 

169. 

188 

170. 

189 

190 

171. 

172. 

195 

173- 

196 

198 

174. 

199 

!75- 

199 

176. 

2OI 

177. 

178. 

2O6 

208 

179. 

209 

180. 

210 

181. 

2IO 

182. 

183. 

211 

212 

184. 

2I4 

185. 

2I5 

1  86. 

216 

187. 

1  88. 

217 

189. 

217 

190. 

218 

191. 

192. 

219 

193- 

220 

194. 

195- 

221 

196. 

197. 

198. 

222 

199. 

200. 

223 

2OI. 

Molar   tooth   of    Micru- 

lestes  antiyuuSi     .         .  223 

Myrmecobiiis  fasciatns,    .  224 
Generalised    section    of 

the  Jurassic  rocks,        .  229 

Mantdlia  megalophylla,  230 

Thecosmilia  annularis,  .  231 

Pentacrimis  fasciculosus,  232 

Hemicidaris  crenularis,  .  233 

JEryon  arctiformis,          ,  234 
Group  of  Jurassic   Bra- 

chiopods,     .         .         .  235 
Ostrea  Mars  hit,      .          .236 

Gryphcea  incurva,  .         .  236 

Diceras  arietina,    .         .  236 

Nerincea  Goodhallii,        .  237 
Ammonites     Hutnphresi- 

amts,           .         .         .  238 

Ammonites  bifrons,          .  238 

Beloteuthis  subcostata,     .  240 
Belemnite  restored  ;  dia- 
gram   of    Belemnite  ; 

Belemnites  canaliculata,  241 
Tetragonolepis,        .         .241 

Acrodus  nobilis,      .         .  242 

Ichthyosaurus  com  munis,  242 

Plesiosaurus  dolichodeirus^  244 
Pterodactylus     crassiros- 

tris,     ....  246 
Ramphorhynchus    Buck- 

landi,  restored,    .         .  248 

Skull  of  Megalosaurus,  .  249 

Arch<zopteryx  macrura,  252 

Archczopteryx,  restored,  252 
Jaw    of    Amphitheriuin 

Prevostii,    .         .         .254 
Jaws   of   Oolitic    Mam- 
mals,          .         .         .  254 
Generalised    section    of 

the  Cretaceous  rocks,  .  260 

Cretaceous  Angiosperms,  263 

Rotalia  Boueana,    .         .  264 

Siphonia  ficus,        .          .  265 

Ventriculites  simplex,      .  265 

Synhelia  Sharpeana,       ,  266 

Galerites  albogalerus,       .  267 

Discoidea  cylindrica,       .  267 

Escharina  Oceani,           .  268 

Terebratella  Astieriana,  .  268 

Crania  Ignabergensis,     .  269 

Ostrea  Couloni,       .         .  269 

Spondylus  spinosus,         .  270 

Inoceramus  sulcatus,       .  270 

Hippurites  Toucasiana,  .  271 
Valuta  elongata,     .         .271 

Nautilus  Danicus,          .  272 


LIST   OF   ILLUSTRATIONS. 


202.  Ancyloceras    Matheroni- 

anus,  .         . 

203.  Turrilites  catenates, 

204.  Forms     of     Cretaceous 

Ammonitidcz, 

205.  Bclemniiella  mucronata, 

206.  Tooth  of  Hybodus, 

207.  Fin-spine  of  Hybodus ;    . 

208.  Beryx    Lewesiensis    and 

Osmeroides  Mantelli,    . 

209.  Teeth  of  Iguanodon, 

210.  Skull     of     Mosasaurus 

Camperi,     .         . 

211.  Chelone  Bensttdi,    . 

212.  Jaws    and    vertebrae    of 

Odontornithes,      .         . 

213.  Fruit  of  Nipadites, 

214.  Nummulina2cEvigata, 

215.  Turbinolia  sulcata, 

2 1 6.  Cardita  planicosta, 

217.  Typhis  tubifer, 

218.  Cypr&a  elegans, 

219.  Cerithium  hexagonum,   . 

220.  Limncea  pyramidalis, 

221.  Physa  columnaris, 

222.  Cyclostoma  Arnoudii, 

223.  Rhombus  minimus, 

224.  Otodus  obliquus, 

225.  Myliobatis  Edward  sit,    . 

226.  Upper  jaw  of  Alligator, 

227.  Skull,  of     Odontopteryx 

toliapicus,    . 

228.  Zeitglodon  cet aides, 

229.  Palceotherium    magnum, 

restored, 

230.  Feet  of  Equid&,     . 

231.  Anoplotherium  commune, 

232.  Skull  of  Dinoceras  mir- 

abilis, 

233.  Vespertilio  Parisiensis,    . 

234.  Miocene  Palms,     . 

235.  Platanus  aceroides, 

236.  Cinnamomum   polymor- 

phum, 

237.  Textttfaria  Meyeriana,  . 

238.  Scutclla  subrotunda, 


239- 

273 

240. 

274 

241. 

242. 

274   243. 

275 

275   244. 

275   245. 

i  246. 

276   247. 

278 

279 

248. 

280 

249. 

282 

250. 

290 

291 

25J- 

292 

293 

252. 

293 

293 

253- 

294 

294 

254- 

294 

255- 

294 

295 

256. 

296 

296 

257- 

297 

258. 

259- 

298 

260. 

299 

261. 

262. 

301 

263. 

302 

3°3 

264. 

304 

265. 

305 

266. 

309 

267. 

309 

Hyaka  Orbignyana,       . 
Tooth  of  Oxyrhina,        . 
Tooth  of  Carcharodon, 
Andrias  Scheuchzeri,       . 
Skull   of  Brontotheriitm 

ingens,         .         .         . 
flipf-  opota  m  us  Siva  ten  sis, 
Skull  of  Sivatheriitm,     . 
Skull  of  Ueinof/ieriiim, 
Tooth  of  Elephas  plant- 

irons  and  of  Mastodon 


309 
312 


Jaw  of  Pliopithecns, 
Rhinoceros  Etruscus  and 

R.  megarhimis,    . 
Molar  tooth  of  Mastodon 

Arvernensis, 
Molar  tooth  of  Elephas 

meridionalis, 
Molar  tooth  of  Elephas 

antiqims,     . 
Skull  and  tooth  of  Ma- 

chairodus  cultridens,     . 
Pecten  Jslandicus, 
Diagram     of   high-level 

and  low-level  gravels, 
Diagrammatic  section  of 

Cave, 
Dinornis  elephantopus,   . 

258.  Skull  of  Diprotodon, 

259.  Skull  of  Thylacoleo, 

260.  Skeleton  of  Megatherium, 
Skeleton  of  Mylodon,     . 
Glyptodon  clavipes, 
Skull  of  Rhinoceros  ticho- 

rhinus, 

264.  Skeleton  of  Cervus  mega- 

ceros, 

265.  Skull  of  Bos pnmigenius, 

266.  Skeleton  of  Mammoth, 

lolar    tooth    of   Mam- 
moth,       -  . 

268.  Skull  of  Ursus  spelanis, 

269.  Skull   of  Hy<?na  spelcea, 

270.  Lower  jaw   of    Trogon- 

therium  Ciivieri,  . 


312 
313 
313 
314 

316 
3  1  8 
319 
320 


321 

323 

328 
329 
350 
330 

331 

338 

340 

343 
347 
348 
349 
350 
352 
352 

353 

355 
356 
358 

359 
360 
361 

361 


PART    I. 


PRINCIPLES    OF    PALEONTOLOGY. 


THE 

ANCIENT    LIFE-HISTORY 


OF 


THE     EARTH, 


INTRODUCTION. 
THE  LAWS  OF  GEOLOGICAL  ACTION. 

UNDER  the  general  title  of  "  Geology  "  are  usually  included  at 
least  two  distinct  branches  of  inquiry,  allied  to  one  another  in 
the  closest  manner,  and  yet  so  distinct  as  to  be  largely  capable 
of  separate  study.  Geology,*  in  its  strict  sense,  is  the  science 
which  is  concerned  with  the  investigation  of  the  materials  which 
compose  the  earth,  the  methods  in  which  those  materials  have 
been  arranged,  and  the  causes  and  modes  of  origin  of  these 
arrangements.  In  this  limited  aspect,  Geology  is  nothing  more 
than  the  Physical  Geography  of  the  past,  just  as  Physical  Geo- 
graphy is  the  Geology  of  to-day;  and  though  it  has  to  call  in 
the  aid  of  Physics,  Astronomy,  Mineralogy,  Chemistry,  and 
other  allies  more  remote,  it  is  in  itself  a  perfectly  distinct  and 
individual  study.  One  has,  however,  only  to  cross  the  thresh- 
old of  Geology  to  discover  that  the  field  and  scope  of  the 
science  cannot  be  thus  rigidly  limited  to  purely  physical  pro- 
blems. The  study  of  the  physical  development  of  the  earth 
throughout  past  ages  brings  us  at  once  in  contact  with  the 
forms  of  animal  and  vegetable  life  which  peopled  its  surface  in 
bygone  epochs,  and  it  is  found  impossible  adequately  to  com- 
*  Gr.  ge,  the  earth  ;  logos,  a  discourse. 


2         PRINCIPLES  OF  PALEONTOLOGY. 

prebend  the  former,  unless  we  possess  some  knowledge  of  the 
latter.  However  great  its  physical  advances  may  be,  Geology 
remains  imperfect  till  it  is  wedded  with  Palaeontology,*  a  study 
which  essentially  belongs  to  the  vast  complex  of  the  Biologi- 
cal Sciences,  but  at  the  same  time  has  its  strictly  geological 
side.  Dealing,  as  it  does,  wholly  with  the  consideration  of 
such  living  beings  as  do  not  belong  exclusively  to  the  present 
order  of  things,  Palaeontology  is,  in  reality,  a  branch  of  Natu- 
ral History,  and  may  be  regarded  as  substantially  the  Zoology 
and  Botany  of  the  past.  It  is  the  ancient  life-history  of  the 
earth,  as  revealed  to  us  by  the  labours  of  palaeontologists, 
with  which  we  have  mainly  to  do  here  ;  but  before  entering 
upon  this,  there  are  some  general  questions,  affecting  Geology 
and  Palaeontology  alike,  which  may  be  very  briefly  discussed. 

The  working  geologist,  dealing  in  the  main  with  purely  phy- 
sical problems,  has  for  his  object  to  determine  the  material 
structure  of  the  earth,  and  to  investigate,  as  far  as  may  be,  the 
long  chain  of  causes  of  which  that  structure  is  the  ultimate  re- 
sult. No  wider  or  more  extended  field  of  inquiry  could  be 
found;  but  philosophical  geology  is  not  content  with  this.  At 
all  the  confines  of  his  science,  the  transcendental  geologist 
finds  himself  confronted  with  some  of  the  most  stupendous 
problems  which  have  ever  engaged  the  restless  intellect  of 
humanity.  The  origin  and  primaeval  constitution  of  the  terres- 
trial globe,  the  laws  of  geologic  action  through  long  ages  of 
vicissitude  and  development,  the  origin  of  life,  the  nature  and 
source  of  the  myriad  complexities  of  living  beings,  the  advent 
of  man,  possibly  even  the  future  history  of  the  earth,  are 
amongst  the  questions  with  which  the  geologist  has  to  grapple 
in  his  higher  capacity. 

These  are  problems  which  have  occupied  the  attention  of 
philosophers  in  every  age  of  the  world,  and  in  periods  long 
antecedent  to  the  existence  of  a  science  of  geology.  The  mere 
existence  of  cosmogonies  in  the  religion  of  almost  every  nation, 
both  ancient  and  modern,  is  a  sufficient  proof  of  the  eager  de- 
sire of  the  human  mind  to  know  something  of  the  origin  of  the 
earth  on  which  we  tread.  Every  human  being  who  has  gazed 
on  the  vast  panorama  of  the  universe,  though  it  may  have  been 
but  with  the  eyes  of  a  child,  has  felt  the  longing  to  solve,  how- 
ever imperfectly,  "  the  riddle  of  the  painful  earth,"  and  has, 
consciously  or  unconsciously,  elaborated  some  sort  of  a  theory 
as  to  the  why  and  wherefore  of  what  he  sees.  Apart  from  the 
profound  and  perhaps  inscrutable  problems  which  lie  at  the 
bottom  of  human  existence,  men  have  in  all  ages  invented 
*  Gr.  palaios,  ancient  ;  onta,  beings  ;  logos,  discourse. 


THE    LAWS   OF   GEOLOGICAL   ACTION.     (  3 

theories  to  explain  the  common  phenomena  of  the  material 
universe  ;  and  most  of  these  theories,  however  varied  in  their 
details,  turn  out  on  examination  to  have  a  common  root,  and 
to  be  based  on  the  same  elements.  Modern  geology  has  its 
own  theories  on  the  same  subject,  and  it  will  be  well  to  glance 
for  a  moment  at  the  principles  underlying  the  old  and  the  new 
views. 

It  has  been  maintained,  as  a  metaphysical  hypothesis,  that 
there  exists  in  the  mind  of  man  an  inherent  principle,  in  virtue 
of  which  he  believes  and  expects  that  what  has  been,  will  be  ; 
and  that  the  course  of  nature  will  be  a  continuous  and  unin- 
terrupted one.  So  far,  however,  from  any  such  belief  existing 
as  a  necessary  consequence  of  the  constitution  of  the  human 
mind,  the  real  fact  seems  to  be  that  the  contrary  belief  has 
been  almost  universally  prevalent.  In  all  old  religions,  and 
in  the  philosophical  systems  of  almost  all  ancient  nations,  the 
order  of  the  universe  has  been  regarded  as  distinctly  unstable, 
mutable,  and  temporary.  A  beginning  and  an  end  have  always 
been  assumed,  and  the  course  of  terrestrial  events  between 
these  two  indefinite  points  has  been  regarded  as  liable  to  con- 
stant interruption  by  revolutions  and  catastrophes  of  different 
kinds,  in  many  cases  emanating  from  supernatural  sources. 
Few  of  the  more  ancient  theological  creeds,  and  still  fewer  of 
the  ancient  philosophies,  attained  body  and  shape  without 
containing,  in  some  form  or  another,  the  belief  in  the  existence 
of  periodical  convulsions,  and  of  alternating  cycles  of  destruc- 
tion and  repair. 

That  geology,  in  its  early  infancy,  should  have  become  im- 
bued with  the  spirit  of  this  belief,  is  no  more  than  might  have 
been  expected ;  and  hence  arose  the  at  one  time  powerful  and 
generally-accepted  doctrine  of  "  Catastrophism."  That  the 
succession  of  phenomena  upon  the  globe,  whereby  the  earth's 
crust  had  assumed  the  configuration  and  composition  which 
we  find  it  to  possess,  had  been  a  discontinuous  and  broken 
succession,  was  the  almost  inevitable  conclusion  of  the  older 
geologists.  Everywhere  in  their  study  of  the  rocks  they  met 
with  apparently  impassable  gaps,  and  breaches  of  continuity 
that  could  not  be  bridged  over.  Everywhere  they  found  them- 
selves conducted  abruptly  from  one  system  of  deposits  to 
others  totally  different  in  mineral  character  or  in  stratigraphical 
position.  Everywhere  they  discovered  that  well-marked  and 
easily  recognisable  groups  of  animals  and  plants  were  succeeded, 
without  the  intermediation  of  any  obvious  lapse  of  time,  by 
other  assemblages  of  organic  beings  of  a  different  character. 
Everywhere  they  found  evidence  that  the  earth's  crust  had 


4  PRINCIPLES   OF   PALEONTOLOGY. 

undergone  changes  of  such  magniir.de  as  to  render  it  seemingly 
irrational  to  suppose  that  they  could  have  been  produced  by 
any  process  now  in  existence.  If  we  add  to  the  above  the 
prevalent  belief  of  the  time  as  to  the  comparative  brevity  of 
the  period  which  had  elapsed  since  the  birth  of  the  globe,  we 
can  readily  understand  the  general  acceptance  of  some  form  of 
catastrophism  amongst  the  earlier  geologists. 

As  regards  its  general  sense  and  substance,  the  doctrine  of 
catastrophism  held  that  the  history  of  the  earth,  since  first  it 
emerged  from  the  primitive  chaos,  had  been  one  of  periods  of 
repose,  alternating  with  catastrophes  and  cataclysms  of  a  more 
or  less  violent  character.  The  periods  of  tranquillity  were  sup- 
posed to  have  been  long  and  protracted ;  and  during  each  of 
them  it  was  thought  that  one  of  the  great  geological  "  forma- 
tions "  was  deposited.  In  each  of  these  periods,  therefore,  the 
condition  of  the  earth  was  supposed  to  be  much  the  same  as  it 
is  now — sediment  was  quietly  accumulated  at  the  bottom  of  the 
sea,  and  animals  and  plants  flourished  uninterruptedly  in  suc- 
cessive generations.  Each  period  of  tranquillity,  however,  was 
believed  to  have  been,  sooner  or  later,  put  an  end  to  by  a 
sudden  and  awful  convulsion  of  nature,  ushering  in  a  brief  and 
paroxysmal  period,  in  which  the  great  physical  forces  were 
unchained  and  permitted  to  spring  into  a  portentous  activity. 
The  forces  of  subterranean  fire,  with  their  concomitant  pheno- 
mena of  earthquake  and  volcano,  were  chiefly  relied  upon  as 
the  efficient  causes  of  these  periods  of  spasm  and  revolution. 
Enormous  elevations  of  portions  of  the  earth's  crust  were  thus 
believed  to  be  produced,  accompanied  by  corresponding  and 
equally  gigantic  depressions  of  other  portions.  Jn  this  way 
new  ranges  of  mountains  were  produced,  and  previously  exist- 
ing ranges  levelled  with  the  ground,  seas  were  converted  into 
dryland,  and  continents  buried  beneath  the  ocean — catastrophe 
following  catastrophe,  till  the  earth  was  rendered  uninhabitable, 
and  its  races  of  animals  and  plants  were  extinguished,  never  to 
reappear  in  the  same  form.  Finally,  it  was  believed  that  this 
feverish  activity  ultimately  died  out,  and  that  the  ancient  peace 
once  more  came  to  reign  upon  the  earth.  As  the  abnormal 
throes  and  convulsions  began  to  be  relieved,  the  dry  land  and 
sea  once  more  resumed  their  relations  of  stability,  the  condi- 
tions of  life  were  once  more  established,  and  new  races  of  ani- 
mals and  plants  sprang  into  existence,  to  last  until  the  super- 
vention of  another  fever-fit. 

Such  is  the  past  history  of  the  globe,  as  sketched  for  us,  in 
alternating  scenes  of  fruitful  peace  and  revolutionary  destruc- 
tion, by  the  earlier  geologists.  As  before  said,  we  cannot 


THE    LAWS   OF   GEOLOGICAL  ACTION.  5 

wonder  at  the  former  general  acceptance  of  Catastrophistic 
doctrines.  Even  in  the  light  of  our  present  widely-increased 
knowledge,  the  series  of  geological  monuments  remains  a  broken 
and  imperfect  one ;  nor  can  we  ever  hope  to  fill  up  completely 
the  numerous  gaps  with  which  the  geological  record  is  defaced. 
Catastrophism  was  the  natural  method  of  accounting  for  these 
gaps,  and,  as  we  shall  see,  it  possesses  a  basis  of  truth.  At 
present,  however,  catastrophism  may  be  said  to  be  nearly  ex- 
tinct, and  its  place  is  taken  by  the  modern  doctrine  of  "  Con- 
tinuity "  or  "  Uniformity" — a  doctrine  with  which  the  name  of 
Lyell  must  ever  remain  imperishably  associated. 

The  fundamental  thesis  of  the  doctrine  of  Uniformity  is, 
that,  in  spite  of  all  apparent  violations  of  continuity,  the  se- 
quence of  geological  phenomena  has  in  reality  been  a  regular 
and  uninterrupted  one ;  and  that  the  vast  changes  which  can 
be  shown  to  have  passed  over  the  earth  in  former  periods  have 
been  the  result  of  the  slow  and  ceaseless  working  of  the  ordi- 
nary physical  forces — acting  with  no  greater  intensity  than  they 
do  now,  but  acting  through  enormously  prolonged  periods. 
The  essential  element  in  the  theory  of  Continuity  is  to  be  found 
in  the  allotment  of  indefinite  time  for  the  accomplishment  of 
the  known  series  of  geological  changes.  It  is  obviously  the 
case,  namely,  that  there  are  two  possible  explanations  of  all 
phenomena  which  lie  so  far  concealed  in  "  the  dark  backward 
and  abysm  of  time,"  that  we  can  have  no  direct  knowledge  of 
the  manner  in  which  they  were  produced.  We  may,  on  the 
one  hand,  suppose  them  to  be  the  result  of  some  very  powerful 
cause,  acting  through  a  short  period  of  time.  That  is  Catas- 
trophism. Or,  we  may  suppose  them  to  be  caused  by  a  much 
weaker  force  operating  through  a  proportionately  prolonged 
period.  This  is  the  view  of  the  Uniformitarians.  It  is  a  ques- 
tion of  energy  versus  time  ;  and  it  is  time  which  is  the  true  ele- 
ment of  the  case.  An  earthquake  may  remove  a  mountain  in 
the  course  of  a  few  seconds ;  but  the  dropping  of  the  gentle 
rain  will  do  the  same,  if  we  extend  its  operations  over  a  millen- 
nium. And  this  is  true  of  all  agencies  which  are  now  at  work, 
or  ever  have  been  at  work,  upon  our  planet.  The  Catastro 
phists,  believing  that  the  globe  is  but,  as  it  were,  the  birth  of 
yesterday,  were  driven  of  necessity  to  the  conclusion  that  its 
history  had  been  checkered  by  the  intermittent  action  of  par- 
oxysmal and  almost  inconceivably  potent  forces.  The  Unifor- 
mitarians, on  the  other  hand,  maintaining  the  "  adequacy  of 
existing  causes,"  and  denying  that  the  known  physical  forces 
ever  acted  in  past  time  with  greater  intensity  than  they  do  at 
present,  are,  equally  of  necessity,  driven  to  the  conclusion  that 


6  PRINCIPLES   OF   PALEONTOLOGY. 

the  world  is  truly  in  its  "  hoary  eld,"  and  that  its  present  state 
is  really  the  result  of  the  tranquil  and  regulated  action  of 
known  forces  through  unnumbered  and  innumerable  centuries. 

The  most  important  point  for  us,  in  the  present  connection, 
is  the  bearing  of  these  opposing  doctrines  upon  the  question 
as  to  the  origin  of  the  existing  terrestrial  order.  On  any  doc- 
trine of  uniformity  that  order  has  been  evolved  slowly,  and, 
according  to  law.  from  a  pre-existing  order.  Any  doctrine  of 
catastrophism,  on  the  other  hand,  carries  with  it,  by  implica- 
tion, the  belief  that  the  present  order  of  things  was  brought 
about  suddenly  and  irrespective  of  any  pre-existent  order ;  and 
it  is  important  to  hold  clear  ideas  as  to  which  of  these  beliefs 
is  the  true  one.  In  the  first  place,  we  may  postulate  that  the 
world  had  a  beginning,  and,  equally,  that  the  existing  terrestrial 
order  had  a  beginning.  However  far  back  we  may  go,  geology 
does  not,  and  cannot,  reach  the  actual  beginning  of  the  world ; 
and  we  are,  therefore,  left  simply  to  our  own  speculations  on 
this  point.  With  regard,  however,  to  the  existing  terrestrial 
order,  a  great  deal  can  be  discovered,  and  to  do  so  is  one  of 
the  principal  tasks  of  geological  science.  The  first  steps  in  the 
production  of  that  order  lie  buried  in  the  profound  and  un- 
searchable depths  of  a  past  so  prolonged  as  to  present  itself  to 
our  finite  minds  as  almost  an  eternity.  The  last  steps  are  in 
the  prophetic  future,  and  can  be  but  dimly  guessed  at.  Be- 
tween the  remote  past  and  the  distant  future,  we  have,  however, 
a  long  period  which  is  fairly  open  to  inspection  ;  and  in  saying 
a  '"long"  period,  it  is  to  be  borne  in  mind  that  this  term  is 
used  in  its  geological  sense.  Within  this  period,  enormously 
long  as  it  is  when  measured  by  human  standards,  we  can  trace 
with  reasonable  certainty  the  progressive  march  of  events,  and 
can  determine  the  laws  of  geological  action,  by  which  the  pre- 
sent order  of  things  has  been  brought  about. 

The  natural  belief  on  this  subject  doubtless  is,  that  the 
world,  such  as  we  now  see  it,  possessed  its  present  form  and 
configuration  from  the  beginning.  Nothing  can  be  more 
natural  than  the  belief  that  the  present  continents  and  oceans 
have  always  been  where  they  are  now;  that  we  have  always 
had  the  same  mountains  and  plains ;  that  our  rivers  have 
always  had  their  present  courses,  and  our  lakes  their  present 
positions ;  that  our  climate  has  always  been  the  same ;  and 
that  our  animals  and  plants  have  always  been  identical  with 
those  now  familiar  to  us.  Nothing  could  be  more  natural 
than  such  a  belief,  and  nothing  could  be  further  removed  from 
the  actual  truth.  On  the  contrary,  a  very  slight  acquaintance 
with  geology  shows  us,  in  the  words  of  Sir  John  Herschel,  that 


THE   LAWS   OF   GEOLOGICAL   ACTION.  7 

"  the  actual  configuration  of  our  continents  and  islands,  the 
coast- lines  of  our  maps,  the  direction  and  elevation  of  our 
mountain-chains,  the  courses  of  our  rivers,  and  the  soundings 
of  our  oceans,  are  not  things  primordially  arranged  in  the  con- 
struction of  our  globe,  but  results  of  successive  and  complex 
actions  on  a  former  state  of  things ;  that,  again,  of  similar 
actions  on  another  still  more  remote ;  and  so  on,  till  the  ori- 
ginal and  really  permanent  state  is  pushed  altogether  out  of 
sight  and  beyond  the  reach  even  of  imagination  ;  while  on  the. 
other  hand,  a  similar,  and,  as  far  as  we  can  see,  interminable 
vista  is  opened  out  for  the  future,  by  which  the  habitability  of 
our  planet  is  secured  amid  the  total  abolition  on  it  of  the 
present  theatres  of  terrestrial  life." 

Geology,  then,  teaches  us  that  the  physical  features  which 
now  distinguish  the  earth's  surface  have  been  produced  as  the 
ultimate  result  of  an  almost  endless  succession  of  precedent 
changes.  Palaeontology  teaches  us,  though  not  yet  in  such 
assured  accents,  the  same  lesson.  Our  present  animals  and 
plants  have  not  been  produced,  in  their  innumerable  forms, 
each  as  we  now  know  it,  as  the  sudden,  collective,  and  simul- 
taneous birth  of  a  renovated  world.  On  the  contrary,  we  have 
the  clearest  evidence  that  some  of  our  existing  animals  and 
plants  made  their  appearance  upon  the  earth  at  a  much  earlier 
period  than  others.  In  the  confederation  of  animated  nature 
some  races  can  boast  of  an  immemorial  antiquity,  whilst  others 
are  comparative  parvenus.  We  have  also  the  clearest  evidence 
that  the  animals  and  plants  which  now  inhabit  the  globe  have 
been  preceded,  over  and  over  again,  by  other  different  assem- 
blages of  animals  and  plants,  which  have  flourished  in  succes- 
sive periods  of  the  earth's  history,  have  reached  their  culmina- 
tion, and  then  have  given  way  to  a  fresh  series  of  living  beings. 
We  have,  finally,  the  clearest  evidence  that  these  successive 
groups  of  animals  and  plants  (faunae  and  florae)  are  to  a  greater 
or  less  extent  directly  connected  with  one  another.  Each 
group  is,  to  a  greater  or  less  extent,  the  lineal  descendant  of 
the  group  which  immediately  preceded  it  in  point  of  time,  and 
is  more  or  less  fully  concerned  with  giving  origin  to  the  group 
which  immediately  follows  it.  That  this  law  of  "  evolution  " 
has  prevailed  to  a  great  extent  is  quite  certain ;  but  it  does  not 
meet  all  the  exigencies  of  the  case,  and  it  is  probable  that  its 
action  has  been  supplemented  by  some  still  unknown  law  of  a 
different  character. 

We  shall  have  to  consider  the  question  of  geological  "  con- 
tinuity" again.  In  the  meanwhile,  it  is  sufficient  to  state  that 
this  doctrine  is  now  almost  universally  accepted  as  the  basis 


8  PRINCIPLES   OF   PALEONTOLOGY. 

of  all  inquiries,  both  in  the  domain  of  geology  and  that  of 
palaeontology.  The  advocates  of  continuity  possess  one  im- 
mense advantage  over  those  who  believe  in  violent  and  revo- 
lutionary convulsions,  that  they  call  into  play  only  agencies 
of  which  we  have  actual  knowledge.  We  know  that  certain 
forces  are'  now  at  work,  producing  certain  modifications  in  the 
present  condition  of  the  globe ;  and  we  know  that  these  forces 
are  capable  of  producing  the  vastest  of  the  changes  which 
geology  brings  under  our  consideration,  provided  we  assign  a 
time  proportionately  vast  for  their  operation.  On  the  other 
hand,  the  advocates  of  catastrophism,  to  make  good  their 
views,  are  compelled  to  invoke  forces  and  actions,  both  de- 
structive and  restorative,  of  which  we  have,  and  can  have,  no 
direct  knowledge.  They  endow  the  whirlwind  and  the  earth- 
quake, the  central  fire  and  the  rain  from  heaven,  with  powers 
as  mighty  as  ever  imagined  in  fable,  and  they  build  up  the 
fragments  of  a  repeatedly  shattered  world  by  the  intervention 
of  an  intermittently  active  creative  power. 

It  should  not  be  forgotten,  however,  that  from  one  point  of 
view   there    is  a  truth  in  catastrophism  which  is  sometimes 
overlooked  by  the  advocates  of  continuity  and  uniformity. 
Catastrophism  has,  as  its  essential  feature,  the  proposition  that 
the  known  and  existing  forces  of  the  earth  at  one  time  acted 
with  much  greater  intensity  and  violence  than  they  do  at  pre- 
sent, and  they  carry  down  the  period  of  this  excessive  action 
to  the  commencement  of  the  present  terrestrial  order.     The 
Uniformitarians,  in  effect,  deny  this  proposition,  at  any  rate  as 
regards  any  period  of  the  earth's  history  of  which  we  have 
actual  cognisance.     If,  however,  the  "  nebular  hypothesis  "  of 
the  origin  of  the  universe  be  well  founded — as  is  generally  ad- 
mitted— then,  beyond  question,  the  earth  is  a  gradually  cooling 
body,  which  has  at  one  time  been  very  much  hotter  than  it  is 
at  present.     There  has  been  a  time,  therefore,  in  which  the 
igneous  forces  of  the  earth,  to  which  we  owe  the  phenomena  of 
earthquakes  and  volcanoes,  must  have  been  far  more  intensely 
active  than  we  can  conceive  of  from  anything  that  we  can  see 
at  the  present  day.     By  the  same  hypothesis,  the  sun  is  a 
cooling  body,  and  must  at  one  time  have  possessed  a  much 
higher  temperature  than  it  has  at  present.     But  increased  heat 
of  the  sun  would  seriously  alter  the  existing  conditions  affect- 
ing the  evaporation  and  precipitation  of  moisture  on  our  earth  ; 
and  hence  the  aqueous  forces  may  also  have  acted  at  one  time 
more  powerfully  than  they  do  now.     The  fundamental  prin- 
ciple of  catastrophism  is,  therefore,  not  wholly  vicious;  and 
we  have  reason  to  think  that  there  must  have  been  periods — 


THE   LAWS   OF   GEOLOGICAL   ACTION.  9 

very  remote,  it  is  true,  and  perhaps  unrecorded  in  the  history 
of  the  earth — in  which  the  known  physical  forces  may  have 
acted  with  an  intensity  much  greater  than  direct  observation 
would  lead  us  to  imagine.  And  this  may  be  believed,  alto- 
gether irrespective  of  those  great  secular  changes  by  which  hot 
or  cold  epochs  are  produced,  and  which  can  hardly  be  called 
"  catastrophistic,"  as  they  are  produced  gradually,  and  are 
liable  to  recur  at  definite  intervals. 

Admitting,  then,  that  there  is  a  truth  at  the  bottom  of  the 
once  current  doctrines  of  catastrophism,  still  it  remains  certain 
that  the  history  of  the  earth  has  been  one  of  law  in  all  past 
time,  as  it  is  now.  Nor  need  we  shrink  back  affrighted  at  the 
vastness  of  the  conception — the  vaster  for  its  very  vagueness 
— that  we  are  thus  compelled  to  form  as  to  the  duration  of 
geological  time.  As  we  grope  our  way  backward  through  the 
dark  labyrinth  of  the  ages,  epoch  succeeds  to  epoch,  and 
period  to  period,  each  looming  more  gigantic  in  its  outlines 
and  more  shadowy  in  its  features,  as  it  rises,  dimly  revealed, 
from  the  mist  and  vapour  of  an  older  and  ever-older  past.  It 
is  useless  to  add  century  to  century  or  millennium  to  millen- 
nium. When  we  pass  a  certain  boundary-line,  which,  after  all, 
is  reached  very  soon,  figures  cease  to  convey  to  our  finite 
faculties  any  real  notion  of  the  periods  with  which  we  have 
to  deal.  The  astronomer  can  employ  material  illustrations 
to  give  form  and  substance  to  our  conceptions  of  celestial 
space ;  but  such  a  resource  is  unavailable  to  the  geologist. 
The  few  thousand  years  of  which  we  have  historical  evidence 
sink  into  absolute  insignificance  beside  the  unnumbered  aeons 
which  unroll  themselves  one  by  one  as  we  penetrate  the  dim 
recesses  of  the  past,  and  decipher  with  feeble  vision  the  pon- 
derous volumes  in  which  the  record  of  the  earth  is  written. 
Vainly  does  the  strained  intellect  seek  to  overtake  an  ever- 
receding  commencement,  and  toil  to  gain  some  adequate  grasp 
of  an  apparently  endless  succession.  A  beginning  there  must 
have  been,  though  we  can  never  hope  to  fix  its  point.  Even 
speculation  droops  her  wings  in  the  attenuated  atmosphere  of 
a  past  so  remote,  and  the  light  of  imagination  is  quenched  in 
the  darkness  of  a  history  so  ancient.  In  time,  as  in  space,  the 
confines  of  the  universe  must  ever  remain  concealed  from  us  , 
and  of  the  end  we  know  no  more  than  of  the  beginning.  In- 
conceivable as  is  to  us  the  lapse  of  ''geological  time,"  it  is  no 
more  than  "a  mere  moment  of  the  past,  a  mere  infinitesimal, 
portion  of  eternity."  Well  may  "  the  human  heart,  that  weeps 
and  trembles,"  say,  with  Richter's  pilgrim  through  celestial 
space,  "  I  will  go  no  farther;  for  the  spirit  of  man  acheth  with 


IO  PRINCIPLES   OF   PALEONTOLOGY. 

this  infinity.  Insufferable  is  the  glory  of  God.  Let  me  lie 
down  in  the  grave,  and  hide  me  from  the  persecution  of  the 
Infinite,  for  end,  I  see,  there  is  none." 


CHAPTER    I. 

THE  SCOPE  AND  MATERIALS  OF  PALEONTOLOGY. 

The  study  of  the  rock-masses  which  constitute  the  crust  of  the 
earth,  if  carried  out  in  the  methodical  and  scientific  manner  of 
the  geologist,  at  once  brings  us,  as  has  been  before  remarked, 
in  contact  with  the  remains  or  traces  of  living  beings  which 
formerly  dwelt  upon  the  globe.  Such  remains  are  found,  in 
greater  or  less  abundance,  in  the  great  majority  of  rocks ;  and 
they  are  not  only  of  great  interest  in  themselves,  but  they  have 
proved  of  the  greatest  importance  as  throwing  light  upon  vari- 
ous difficult  problems  in  geology,  in  natural  history,  in  botany, 
and  in  philosophy.  Their  study  constitutes  the  science  of 
palaeontology ;  and  though  it  is  possible  to  proceed  to  a  cer- 
tain length  in  geology  and  zoology  without  much  palaeontolo- 
gical  knowledge,  it  is  hardly  possible  to  attain  to  a  satisfac- 
tory general  acquaintance  with  either  of  these  subjects  with- 
out having  mastered  the  leading  facts  of  the  first.  Similarly, 
it  is  not  possible  to  study  palaeontology  without  some  ac 
quaintance  with  both  geology  and  natural  history. 

PALAEONTOLOGY,  then,  is  the  science  which  treats  of  the 
living  beings,  whether  animal  or  vegetable,  which  have  in- 
habited the  earth  during  past  periods  of  its  history.  Its  object 
is  to  eludicate,  as  far  as  may  be,  the  structure,  mode  of  exist- 
ence, and  habits  of  all  such  ancient  forms  of  life;  to  determine 
their  position  in  the  scale  of  organised  beings ;  to  lay  down 
the  geographical  limits  within  which  they  flourished ;  and  to 
fix  the  period  of  their  advent  and  disappearance.  It  is  the 
ancient  life-history  of  the  earth  ;  and  were  its  record  complete, 
it  would  furnish  us  with  a  detailed  knowledge  of  the  form  and 
relations  of  all  the  animals  and  plants  which  have  at  any  period 
flourished  upon  the  land-surfaces  of  the  globe  or  inhabited  its 
waters ;  it  would  enable  us  to  determine  precisely  their  succes- 
sion in  time ;  and  it  would  place  in  our  hands  an  unfailing  key 
to  the  problems  of  evolution.  Unfortunately,  from  causes 
which  will  be  subsequently  discussed,  the  palaeontological 
record  is  extremely  imperfect,  and  our  knowledge  is  inter- 


THE   SCOPE   OF   PALvEONTOLOGY.  I  I 

rupted  by  gaps,  which  not  only  bear  a  large  proportion  to  our 
solid  information,  but  which  in  many  cases  are  of  such  a  nature 
that  we  can  never  hope  to  fill  them  up. 

FOSSILS. — The  remains  of  animals  or  vegetables  which  we 
now  find  entombed  in  the  solid  rock,  and  which  constitute  the 
working  material  of  the  palaeontologist,  are  termed  "fossils,"* 
or  "  petrifactions."  In  most  cases,  as  can  be  readily  under- 
stood, fossils  are  the  actual  hard  parts  of  animals  and  plants 
which  were  in  existence  when  the  rock  in  which  they  are  now 
found  was  being  deposited.  Most  fossils,  therefore,  are  of  the 
nature  of  the  shells  of  shell-fish,  the  skeletons  of  coral-zoophytes, 
the  bones  of  vertebrate  animals,  or  the  wood,  bark,  or  leaves 
of  plants.  All  such  bodies  are  more  or  less  of  a  hard  consist- 
ence to  begin  with,  and  are  capable  of  resisting  decay  for  a 
longer  or  shorter  time — hence  the  frequency  with  which  they 
occur  in  the  fossil  condition.  Strictly  speaking,  however,  by 
the  term  "  fossil  "  must  be  understood  "  any  body,  or  the  traces 
of  the  existence  of  any  body,  whether  animal  or  vegetable,  which 
has  been  buried  in  the  earth  by  natural  causes"  (Lyell). 
We  shall  find,  in  fact,  that  many  of  the  objects  which  we  have 
to  study  as  "fossils"  have  never  themselves  actually  formed 
parts  of  any  animal  or  vegetable,  though  they  are  due  to  the 
former  existence  of  such  organisms,  and  indicate  what  was  the 
nature  of  these.  Thus  the  footprints  left  by  birds,  or  reptiles, 
or  quadrupeds  upon  sand  or  mud,  are  just  as  much  proofs  of 
the  former  existence  of  these  animals  as  would  be  bones, 
feathers,  or  scales,  though  in  themselves  they  are  inorganic. 
Under  the  head  of  fossils,  therefore,  come  the  footprints  of 
air-breathing  vertebrate  animals;  the  tracks,  trails,  and  bur- 
rows of  sea-worms,  crustaceans,  or  molluscs ;  the  impressions 
left  on  the  sand  by  stranded  jelly-fishes ;  the  burrows  in  stone 
or  wood  of  certain  shell-fish ;  the  "  moulds "  or  "  casts "  of 
shells,  corals,  and  other  organic  remains ;  and  various  other 
bodies  of  a  more  or  less  similar  nature. 

FOSSILISATION. — The  term  "fossilisation  "  is  applied  to  all 
those  processes  through  which  the  remains  of  organised  beings 
may  pass  in  being  converted  into  fossils.  These  processes  are 
numerous  and  varied ;  but  there  are  three  principal  modes  of 
fossilisation  which  alone  need  be  considered  here.  In  the  first 
instance,  the  fossil  is  to  all  intents  and  purposes  an  actual 
portion  of  the  original  organised  being — such  as  a  bone,  a  shell, 
or  a  piece  of  wood.  In  some  rare  instances,  as  in  the  case  of 
the  body  of  the  Mammoth  discovered  embedded  in  ice  at  the 
mouth  of  the  Lena  in  Siberia,  the  fossil  may  be  preserved 
*  Lat.  fosstts,  dug  up. 


12  PRINCIPLES   OF   PALEONTOLOGY. 

almost  precisely  in  its  original  condition,  and  even  with  its 
soft  parts  uninjured.  More  commonly,  certain  changes  have 
taken  place  in  the  fossil,  the  principal  being  the  more  or  less 
total  removal  of  the  organic  matter  originally  present.  Thus 
bones  become  light  and  porous  by  the  removal  of  their  gela- 
tine, so  as  to  cleave  to  the  tongue  on  being  applied  to  that 
organ ;  whilst  shells  become  fragile,  and  lose  their  primitive 
colours.  In  other  cases,  though  practically  the  real  body  it 
represents,  all  the  cavities  of  the  fossil,  down  to  its  minutest 
recesses,  may  have  become  infiltrated  with  mineral  matter.  It 
need  hardly  be  added,  that  it  is  in  the  more  modern  rocks  that 
we  find  the  fossils,  as  a  rule,  least  changed  from  their  former 
condition;  but  the  original  structure  is  often  more  or  less  com- 
pletely retained  in  some  of  the  fossils  from  even  the  most 
ancient  formations. 

In  the  second  place,  we  very  frequently  meet  with  fossils  in 
the  state  of  "casts"  or  moulds  of  the  original  organic  body. 
What  occurs  in  this  case  will  be  readily  understood  if  we  ima- 
gine any  common  bivalve  shell,  as  an  Oyster,  or  Mussel,  or 
Cockle,  embedded  in  clay  or  mud.  If  the  clay  were  sufficiently 
soft  and  fluid,  the  first  thing  would  be  that  it  would  gain  access 
to  the  interior  of  the  shell,  and  would  completely  fill  up  the 
space  between  the  valves.  The  pressure,  also,  of  the  surround- 
ing matter  would  insure  that  the  clay  would  everywhere  ad- 
here closely  to  the  exterior  of  the  shell.  If  now  we  suppose 
the  clay  to  be  in  any  way  hardened  so  as  to  be  converted  into 
stone,  and  if  we  were  to  break  up  the  stone,  we  should  obvi- 
ously have  the  following  state  of  parts.  The  clay  which  filled 
the  shell  would  form  an  accurate  cast  of  the  interior  of  the 
shell,  and  the  clay  outside  would  give  us  an  exact  impression 
or  cast  of  the  exterior  of  the  shell  (fig.  i).  We  should  have, 

then,  two  casts,  an  interior  and 
an  exterior,  and  the  two  would 
be  very  different  to  one  another, 
since  the  inside  of  a  shell  is 
very  unlike  the  outside.  In 
the  case,  in  fact,  of  many  uni- 
valve shells,  the  interior  cast  or 
"mould"  is  so  unlike  the  ex- 
terior cast,  or  unlike  the  shell 

Fig.  i.  —  Trigoma  longa,  showing  casts     itself,   that  it    may  be  difficult  tO 

Cretecw^N^o^*^111*        ^   determine  the  true  origin  of  the 

former. 

It  only  remains  to  add  that  there  is  sometimes  a  further 
complication.  If  the  rock  be  very  porous  and  permeable  by 


THE   SCOPE   OF   PALEONTOLOGY. 


water,  it  may  happen  that  the  original  shell  is  entirely  dissolved 
away,  leaving  the  interior  cast  loose,  like  the  kernel  of  a  nut, 
within  the  case  formed  by  the  exterior  cast.  Or  it  may  happen 
that  subsequent  to  the  attainment  of  this  state  of  things,  the 
space  thus  left  vacant  between  the  interior  and  exterior  cast — 
tne  space,  that  is,  formerly  occupied  by  the  shell  itself — may 
be  filled  up  by  some  foreign  mineral  deposited  there  by  the 
infiltration  of  water.  In  this  last  case  the  splitting  open  of  the 
rock  would  reveal  an  interior  cast,  an  exterior  cast,  and  finally 
a  body  which  would  have  the  exact  form  of  the  original  shell,  but 
which  would  be  really  a  much  later  formation,  and  which  would 
not  exhibit  under  the  microscope  the  minute  structure  of  shell. 
In  the  third  class  of  cases  we  have  fossils  which  present 
with  the  greatest  accuracy  the  external  form,  and  even  some- 
times the  internal  minute  structure,  of  the  original  organic 
body,  but  which,  nevertheless,  are  not  themselves  truly  organic, 
but  have  been  formed  by  a  "  replacement "  of  the  particles  of 
the  primitive  organism  by  some  mineral  substance.  The  most 
elegant  example  of  this  is  afforded  by  fossil  wood  which  has 
been  "  silicified"  or  converted  into  flint  (silex).  In  such  cases 
we  have  fossil  wood  which  presents  the  rings  of  growth  and 
fibrous  structure  of  recent  wood,  and  which  under  the  micro- 
scope exhibits  the  minutest  vessels  which  characterise  ligneous 
tissue,  together  with  the  even  more  minute  markings  of  the 
vessels  (fig.  2).  The  whole,  however,  instead  of  being  com- 


Fig  2.  —  Microscopic  section  of  the 
silicified  wood  of  a  Conifer  (Sequoia)  cut 
in  the  long  direction  of  the  fibres.  Post- 
tertiary?  Colorado.  (Original.) 


Fig.  3. — Microscopic  section  of  the  wood 
of  the  common  Larch  (Abies  tari.r),  cut  in 
the  long  direction  of  the  fibres.  In  both  the 
fresh  and  the  fossil  wood  (fig.  2)  are  seen 
the  discs  characteristic  of  coniferous  wood. 
(Original.) 


posed  of  the  original  carbonaceous  matter  of  the  wood,  is  now 
converted  into  flint.     The  only  explanation  that  can  be  given 


14  PRINCIPLES    OF   PALEONTOLOGY. 

of  this  by  no  means  rare  phenomenon,  is  that  the  wood  must 
have  undergone  a  slow  process  of  decay  in  water  charged  with 
silica  or  flint  in  solution.  As  each  successive  particle  of  wood 
was  removed  by  decay,  its  place  was  taken  by  a  particle  of 
flint  deposited  from  the  surrounding  water,  till  ultimately  the 
entire  wood  was  silicified.  The  process,  therefore,  resembles 
what  would  take  place  if  we  were  to  pull  down  a  house  built 
of  brick  by  successive  bricks,  replacing  each  brick  as  removed 
by  a  piece  of  stone  of  precisely  the  same  size  and  form.  The 
result  of  this  would  be  that  the  house  would  retain  its  primi- 
tive size,  shape,  and  outline,  but  it  would  finally  have  been 
converted  from  a  house  of  brick  into  a  house  of  stone.  Many 
other  fossils  besides  wood— such  as  shells,  corals,  sponges, 
&c. — are  often  found  silicified  ;  and  this  may  be  regarded  as 
the  commonest  form  of  fossilisation  by  replacement.  In  other 
cases,  however,  though  the  principle  of  the  process  is  the  same, 
the  replacing  substance  may  be  iron  pyrites,  oxide  of  iron, 
sulphur,  malachite,  magnesite,  talc,  &c. ;  but  it  is  rarely  that 
the  replacement  with  these  minerals  is  so  perfect  as  to  preserve 
the  more  delicate  details  of  internal  structure. 


CHAPTER    II. 
THE  FOSSILIFEROUS  ROCKS. 

Fossils  are  found  in  rocks,  though  not  universally  or  pro- 
miscuously ;  and  it  is  therefore  necessary  that  the  palaeonto- 
logist should  possess  some  acquaintance  with,  at  any  rate,  those 
rocks  which  yield  organic  remains,  and  which  are  therefore 
said  to  be  " fossiliferous"  In  geological  language,  all  the 
materials  which  enter  into  the  composition  of  the  solid  crust 
of  the  earth,  be  their  texture  what  it  may — from  the  most  im- 
palpable mud  to  the  hardest  granite — are  termed  "rocks;" 
and  for  our  present  purpose  we  may  divide  these  into  two  great 
groups.  In  the  first  division  are  the  Igneous  Rocks — such  as 
the  lavas  and  ashes  of  volcanoes — which  are  formed  within  the 
body  of  the  earth  itself,  and  which  owe  their  structure  and 
origin  to  the  action  of  heat.  The  Igneous  Rocks  are  formed 
primarily  below  the  surface  of  the  earth,  which  they  only  reach 
as  the  result  of  volcanic  action  ;  they  are  generally  destitute  of 
distinct  "  stratification,"  or  arrangement  in  successive  layers ; 
and  they  do  not  contain  fossils,  except  in  the  comparatively 


THE   FOSSILIFEROUS   ROCKS.  15 

rare  instances  where  volcanic  ashes  have  enveloped  animals 
or  plants  which  were  living  in  the  sea  or  on  the  land  in  the 
immediate  vicinity  of  the  volcanic  focus.  The  second  great 
division  of  rocks  is  that  of  the  Fossiliferous,  Aqueous,  or  Sedi- 
mentary Rocks.  These  are  formed  at  the  surface  of  the  earth, 
and,  as  implied  by  one  of  their  names,  are  invariably  deposited 
in  water.  They  are  produced  by  vital  or  chemical  action,  or 
are  formed  from  the  "  sediment "  produced  by  the  disintegra- 
tion and  reconstruction  of  previously  existing  rocks,  without 
previous  solution  ;  they  mostly  contain  fossils ;  and  they  are 
arranged  in  distinct  layers  or  "strata."  The  so-called  "aerial" 
rocks  which,  like  beds  of  blown  sand,  have  been  formed  by 
the  action  of  the  atmosphere,  may  also  contain  fossils ;  but 
they  are  not  of  such  importance  as  to  require  special  notice 
here. 

For  all  practical  purposes,  we  may  consider  that  the  Aque- 
ous Rocks  are  the  natural  cemetery  of  the  animals  and  plants 
of  bygone  ages ;  and  it  is  therefore  essential  that  the  palaeon- 
tological  student  should  be  acquainted  with  some  of  the  prin- 
cipal facts  as  to  their  physical  characters,  their  minute  structure 
and  mode  of  origin,  their  chief  varieties,  and  their  historical 
succession. 

The  Sedimentary  or  Fossiliferous  Rocks  form  the  greater 
portion  of  that  part  of  the  earth's  crust  which  is  open  to  our 
examination,  and  are  distinguished  by  the  fact  that  they  are 
regularly  "  stratified"  or  arranged  in  distinct  and  definite  layers 
or  "  strata."  These  layers  may  consist  of  a  single  material, 
as  in  a  block  of  sandstone,  or  they  may  consist  of  different 
materials.  When  examined  on  a  large  scale,  they  are  always 
found  to  consist  of  alternations  of  layers  of  different  mineral 
composition.  We  may  examine  any  given  area,  and  find  in  it 
nothing  but  one  kind  of  rock — sandstone,  perhaps,  or  lime- 
stone. In  all  cases,  however,  if  we  extend  our  examination 
sufficiently  far,  we  shall  ultimately  come  upon  different  rocks ; 
and,  as  a  general  rule,  the  thickness  of  any  particular  set  of 
beds  is  comparatively  small,  so  that  different  kinds  of  rock 
alternate  with  one  another  in  comparatively  small  spaces. 

As  regards  the  origin  of  the  Sedimentary  Rocks,  they  are 
for  the  most  part  "  derivative  "  rocks,  being  derived  from  the 
wear  and  tear  of  pre-existent  rocks.  Sometimes,  however,  they 
owe  their  origin  to  chemical  or  vital  action,  when  they  would 
more  properly  be  spoken  of  simply  as  Aqueous  Rocks.  As  to 
their  mode  of  deposition,  we  are  enabled  to  infer  that  the 
materials  which  compose  them  have  formerly  been  spread  out 
by  the  action  of  water,  from  what  we  see  going  on  every  day 


10  PRINCIPLES   OF    PALAEONTOLOGY. 

at  the  mouths  of  our  great  rivers,  and  on  a  smaller  scale  wher- 
ever there  is  running  water.     Every  stream,  where  it  runs  into 


Fig.  4. — Sketch  of  Carboniferous  strata  at  Kinghorn.  in  Fife,  showing  stratified  beds 
(limestone  and  shales)  surmounted  by  an  unstratified  mass  of  trap.     (Original.) 

a  lake  or  into  the  sea,  carries  with  it  a  burden  of  mud,  sand, 
and  rounded  pebbles,  derived  from  the  waste  of  the  rocks 
which  form  its  bed  and  banks.  When  these  materials  cease 
to  be  impelled  by  the  force  of  the  moving  water,  they  sink  to 
the  bottom,  the  heaviest  pebbles,  of  course,  sinking  first,  the 
smaller  pebbles  and  sand  next,  and  the  finest  mud  last.  Ulti- 
mately, therefore,  as  might  have  been  inferred  upon  theoretical 
grounds,  and  as  is  proved  by  practical  experience,  every  lake 
becomes  a  receptacle  for  a  series  of  stratified  rocks  produced 
by  the  streams  flowing  into  it.  These  deposits  may  vary  in 
different  parts  of  the  lake,  according  as  one  stream  brought 
down  one  kind  of  material  and  another  stream  contributed 
another  material ;  but  in  all  cases  the  materials  will  bear  ample 
evidence  that  they  were  produced,  sorted,  and  deposited  by 
running  water.  The  finer  beds  of  clay  or  sand  will  all  be 
arranged  in  thicker  or  thinner  layers  or  laminae;  and  if  there 
are  any  beds  of  pebbles  these  will  all  be  rounded  or  smooth, 
just  like  the  water-worn  pebbles  of  any  brook-course.  In  all 
probability,  also,  we  should  find  in  some  of  the  beds  the  re- 


THE   FOSSILIFEROUS   ROCKS.  I/ 

mains  of  fresh-water  shells  or  plants  or  other  organisms  which 
inhabited  the  lake  at  the  time  these  beds  were  being  de- 
posited. 

In  the  same  way  large  rivers  —  such  as  the  Ganges  or 
Mississippi — deposit  all  the  materials  which  they  bring  down 
at  their  mouths,  forming  in  this  way  their  "deltas."  When- 
ever such  a  delta  is  cut  through,  either  by  man  or  by  some 
channel  of  the  river  altering  its  course,  we  find  that  it  is  com- 
posed of  a  succession  of  horizontal  layers  or  strata  of  sand  or 
mud,  varyjng  in  mineral  composition,  in  structure,  or  in  grain, 
according  to  the  nature  of  the  materials  brought  down  by  the 
river  at  different  periods.  Such  deltas,  also,  will  contain  the 
remains  of  animals  which  inhabit  the  river,  with  fragments  of 
the  plants  which  grew  on  its  banks,  or  bones  of  the  animals 
which  lived  in  its  basin. 

Nor  is  this  action  confined,  of  course,  to  large  rivers  only, 
though  naturally  most  conspicuous  in  the  greatest  bodies  of 
water.  On  the  contrary,  all  streams,  of  whatever  size,  are 
engaged  in  the  work  of  wearing  down  the  dry  land,  and  of 
transporting  the  materials  thus  derived  from  higher  to  lower 
levels,  never  resting  in  this  work  till  they  reach  the  sea. 


f          /         „'        '      7    X       X     -          *  '       *      '      *  -.£    s   _/r    ^   S 

Fig    5.— Dia^ra.u  10  illustrate  the  formation  of  sedimentary  deposits  at  the  point 
where  a  river  debouches  into  the  sea. 


Lastly,  the  sea  itself — irrespective  of  the  materials  delivered 
into  it  by  rivers — is  constantly  preparing  fresh  stratified  de- 


1 8  PRINCIPLES   OF   PALEONTOLOGY. 

posits  by  its  own  action.  Upon  every  coast-line  the  sea  is 
constantly  eating  back  into  the  land  and  reducing  its  com- 
ponent rocks  to  form  the  shingle  and  sand  which  we  see  upon 
every  shore.  The  materials  thus  produced  are  not,  however, 
lost,  but  are  ultimately  deposited  elsewhere  in  the  form  of  new 
stratified  accumulations,  in  which  are  buried  the  remains  of 
animals  inhabiting  the  sea  at  the  time. 

Whenever,  then,  we  find  anywhere  in  the  interior  of  the  land 
any  series  of  beds  having  these  characters — composed,  that  is, 
of  distinct  layers,  the  particles  of  which,  both  large  and  small, 
show  distinct  traces  of  the  wearing  action  of  water — whenever 
and  wherever  we  find  such  rocks,  we  are  justified  in  assuming 
that  they  have  been  deposited  by  water  in  the  manner  above 
mentioned.  Either  they  were  laid  down  in  some  former  lake 
by  the  combined  action  of  the  streams  which  flowed  into  it ; 
or  they  were  deposited  at  the  mouth  of  some  ancient  river, 
forming  its  delta ;  or  they  were  laid  down  at  the  bottom  of  the 
ocean.  In  the  first  two  cases,  any  fossils  which  the  beds 
might  contain  would  be  the  remains  of  fresh-water  or  terres- 
trial organisms.  In  the  last  case,  the  majority,  at  any  rate,  of 
the  fossils  would  be  the  remains  of  marine  animals. 

The  term  "  formation  "  is  employed  by  geologists  to  express 
"  any  group  of  rocks  which  have  some  character  in  common, 
whether  of  origin,  age,  or  composition "  (Lyell) ;  so  that  we 
may  speak  of  stratified  and  unstratified  formations,  aqueous 
or  igneous  formations,  fresh-water  or  marine  formations,  and 
so  on. 

CHIEF  DIVISIONS  OF  THE  AQUEOUS  ROCKS. 

The  Aqueous  Rocks  may  be  divided  into  two  great  sections, 
the  Mechanically-formed  and  the  Chemically-formed,  includ- 
ing under  the  last  head  all  rocks  which  owe  their  origin  to 
vital  action,  as  well  as  those  produced  by  ordinary  chemical 
agencies. 

A.  MECHANICALLY-FORMED  ROCKS.  —  These  are  all  those 
Aqueous  Rocks  of  which  we  can  obtain  proofs  that  their 
particles  have  been  mechanically  transported  to  their  present 
situation.  Thus,  if  we  examine  a  piece  of  conglomerate  or 
puddingstone,  we  find  it  to  be  compos :d  of  a  number  of 
rounded  pebbles  embedded  in  an  enveloping  matrix  or  paste, 
which  is  usually  of  a  sandy  nature,  but  may  be  composed  of 
carbonate  of  lime  (when  the  rock  is  said  to  be  a  "  calcareous 
conglomerate  ").  The  pebbles  in  all  conglomerates  are  worn 
and  rounded  by  the  action  of  water  in  motion,  and  thus  show 


THE   FOSSILIFEROUS   ROCKS. 


19 


that  they  have  been  subjected  to  much  mechanical  attrition, 
whilst  they  have  been  mechanically  transported  for  a  greater 
or  less  distance  from  the  rock  of  which  they  originally  formed 
part.  The  analogue  of  the  old  conglomerates  at  the  present 
day  is  to  be  found  in  the  great  beds  of  shingle  and  gravel 
which  are  formed  by  the  action  of  the  sea  on  every  coast-line, 
and  which  are  composed  of  water-worn  and  well-rounded 
pebbles  of  different  sizes.  A  breccia  is  a  mechanically-formed 
rock,  very  similar  to  a  conglomerate,  and  consisting  of  larger 
or  smaller  fragments  of  rock  embedded  in  a  common  matrix. 
The  fragments,  however,  are  in  this  case  all  more  or  less 
angular,  and  are  not  worn  or  rounded.  The  fragments  in 
breccias  may  be  of  large  size,  or  they  may  be  comparatively 
small  (fig.  6);  and  the  matrix  may  be  composed  of  sand  (aren- 
aceous) or  of  carbonate  of 
lime  (calcareous).  In  the  case 
of  an  ordinary  sandstone,  again, 
we  have  a  rock  which  may  be 
regarded  as  simply  a  very  fine- 
grained conglomerate  or  brec- 
cia, being  composed  of  small 
grains  of  sand  (silica),  some- 
timesrounded,  sometimes  more 
or  less  angular,  cemented  to- 
gether by  some  such  substance 
as  oxide  of  iron,  silicate  of 
iron,  or  carbonate  of  lime.  A 

Sandstone,     therefore,      like 
i«s 

is  >  . 

rOCk,   itS    COmpO-     The  fragments  are  all  of  small   size,   and 

nent  grains  being  equally  the  ^  ^fe^dtmStm! 
result  of  mechanical  attrition  /Q^f^V  matrix  of  crystalline  limestone. 
and  having  equally  been  trans- 

ported from  a  distance  ;  and  the  same  is  true  of  the  ordinary 
sand  of  the  sea-shore,  which  is  nothing  more  than  an  uncon- 
solidated  sandstone.  Other  so-called  sands  and  sandstones, 
though  equally  mechanical  in  their  origin,  are  truly  calcareous 
in  their  nature,  and  are  more  or  less  entirely  composed  of 
carbonate  of  lime.  Of  this  kind  are  the  shell-sand  so  com- 
mon on  our  coasts,  and  the  coral-  sand  which  is  so  largely 
formed  in  the  neighbourhood  of  coral-reefs.  In  these  cases 
the  rock  is  composed  of  fragments  of  the  skeletons  of  shell- 
fish, and  numerous  other  marine  animals,  together,  in  many 
instances,  with  the  remains  of  certain  sea-weeds  (Corallines, 
Nullipores,  &c.)  which  are  endowed  with  the  power  of  secret- 


a         Fig.  6  -Microscopic  section  of  a  calcare- 
a     rnprl-iini       ous  breccia  in  the  Lower  Silurian  (Coniston 

a   mecnani-   LimestOMe)  of  Shap  Wells>  Westmoreland. 


20  PRINCIPLES   OF    PALEONTOLOGY. 

ing  carbonate  of  lime  from  the  sea-water.  Lastly,  in  cer- 
tain rocks  still  finer  in  their  texture  than  sandstones,  such 
as  the  various  mud-rocks  and  shales,  we  can  still  recognise  a 
mechanical  source  and  origin.  If  slices  of  any  of  these  rocks 
sufficiently  thin  to  be  transparent  are  examined  under  the 
microscope,  it  will  be  found  that  they  are  composed  of  minute 
grains  of  different  sizes,  which  are  all  more  or  less  worn  and 
rounded,  and  which  clearly  show,  therefore,  that  they  have 
been  subjected  to  mechanical  attrition. 

All  the  above-mentioned  rocks,  then,  are  mechanically-formed 
rocks;  and  they  are  often  spoken  of  as  "  Derivative  Rocks," 
in  consequence  of  the  fact  that  their  particles  can  be  shown  to 
have  been  mechanically  derived  from  other  pre-existent  rocks. 
It  follows  from  this  that  every  bed  of  any  mechanically-formed 
rock  is  the  measure  and  equivalent  of  a  corresponding  amount 
of  destruction  of  some  older  rock.  It  is  not  necessary  to 
enter  here  into  a  minute  account  of  the  subdivisions  of  these 
rocks,  but  it  may  be  mentioned  that  they  may  be  divided  into 
two  principal  groups,  according  to  their  chemical  composition. 
In  the  one  group  we  have  the  so-called  Arenaceous  (Lat  arena, 
sand)  or  Siliceous  Rocks,  which  are  essentially  composed  of 
larger  or  smaller  grains  of  flint  or  silica.  In  this  group  are 
comprised  ordinary  sand,  the  varieties  of  sandstone  and  grit, 
and  most  conglomerates  and  breccias.  We  shall,  however,  after- 
wards see  that  some  siliceous  rocks  are  of  organic  origin.  In 
the  second  group  are  the  so-called  Argillaceous  (Lat.  argilla, 
clay)  Rocks,  which  contain  a  larger  or  smaller  amount  of  clay  or 
hydrated  silicate  of  alumina  in  their  composition.  Under  this 
head  come  clays,  shales,  marls,  marl-slate,  clay-slates,  and 
most  flags  and  flagstones. 

B.  CHEMICALLY-FORMED  ROCKS. — In  this  section  are  com- 
prised all  those  Aqueous  or  Sedimentary  Rocks  which  have 
been  formed  by  chemical  agencies.  As  many  of  these  chemi- 
cal agencies,  however,  are  exerted  through  the  medium  of 
living  beings,  whether  animals  or  plants,  we  get  into  this 
section  a  number  of  what  may  be  called  "  organically -formed 
rocks"  These  are  of  the  greatest  possible  importance  to  the 
palaeontologist,  as  being  to  a  greater  or  less  extent  composed 
of  the  actual  remains  of  animals  or  vegetables,  and  it  will 
therefore  be  necessary  to  consider  their  character  and  struc- 
ture in  some  detail. 

By  far  the  most  important  of  the  chemically-formed  rocks 
are  the  so-called  Calcareous  Rocks  (Lat.  calx,  lime),  com- 
prising all  those  which  contain  a  large  proportion  of  carbonate 
of  lime,  or  are  wholly  composed  of  this  substance.  Carbonate 


THE    FOSSILIFEROUS   ROCKS.  21 

of  lime  is  soluble  in  water  holding  a  certain  amount  of  car- 
bonic acid  gas  in  solution ;  and  it  is,  therefore,  found  in  larger 
or  smaller  quantity  dissolved  in  all  natural  waters,  both  fresh 
and  salt,  since  these  waters  are  always  to  some  extent  charged 
with  the  above-mentioned  solvent  gas.  A  great  number  of 
aquatic  animals,  however,  together  with  some  aquatic  plants, 
are  endowed  with  the  power  of  separating  the  lime  thus  held 
in  solution  in  the  water,  and  of  reducing  it  again  to  its  solid 
condition.  In  this  way  shell-fish,  crustaceans,  sea-urchins, 
corals,  and  an  immense  number  of  other  animals,  are  enabled 
to  construct  their  skeletons  ;  whilst  some  plants  form  hard 
structures  within  their  tissues  in  a  precisely  similar  manner. 
\Ve  do  meet  with  some  calcareous  deposits,  such  as  the 
"stalactites"  and  "stalagmites"  of  caves,  the  "calcareous 
tufa"  and  "travertine"  of  some  hot  springs,  and  the  spongy 
calcareous  deposits  of  so-called  "  petrifying  springs,"  which 
are  purely  chemical  in  their  origin,  and  owe  nothing  to  the 
operation  of  living  beings.  Such  deposits  are  formed  simply 
by  the  precipitation  of  carbonate  of  lime  from  water,  in  con- 
sequence of  the  evaporation  from  the  water  of  the  carbonic 
acid  gas  which  formerly  held  the  lime  in  solution  ;  but,  though 
sometimes  forming  masses  of  considera'Je  thickness  and  of 
geological  importance,  they  do  not  concern  us  here.  Almost 
all  the  limestones  which  occur  in  the  series  of  the  stratified 
rocks  are,  primarily  at  any  rate,  of  organic  origin,  and  have 
been,  directly  or  indirectly,  produced  by  the  action  of  certain 
lime-making  animals  or  plants,  or  both  combined.  The  pre- 
sumption as  to  all  the  calcareous  rocks,  which  cannot  be 
clearly  shown  to  have  been  otherwise  produced,  is  that  they 
are  thus  organically  formed  ;  and  in  many  cases  this  presump- 
tion can  be  readily  reduced  to  a  certainty.  There  are  many 
varieties  of  the  calcareous  rocks,  but  the  following  are  those 
which  are  of  the  greatest  importance  : — 

Chalk  is  a  calcareous  rock  of  a  generally  soft  and  pulver- 
ulent texture,  and  with  an  earthy  fracture.  It  varies  in  its 
purity,  being  sometimes  almost  wholly  composed  of  carbonate 
of  lime,  and  at  other  times  more  or  less  intermixed  with  foreign 
matter.  Though  usually  soft  and  readily  reducible  to  powder, 
chalk  is  occasionally,  as  in  the  north  of  Ireland,  tolerably  hard 
and  compact ;  but  it  never  assumes  the  crystalline  aspect 
and  stony  density  of  limestone,  except  it  be  in  immediate 
contact  with  some  mass  of  igneous  rock.  By  means  of  the 
microscope,  the  true  nature  and  mode  of  formation  of  chalk 
can  be  determined  with  the  greatest  ease.  In  the  case  of  the 
harder  varieties,  the  examination  can  be  conducted  bv  means 


22 


PRINCIPLES   OF   PALEONTOLOGY. 


of  slices  ground  down  to  a  thinness  sufficient  to  render  them 
transparent ;  but  in  the  softer  kinds  the  rock  must  be  disinte- 
grated under  water,  and  the  debris  examined  microscopically. 
When  investigated  by  either  of  these  methods,  chalk  is  found 
to  be  a  genuine  organic  rock,  being  composed  of  the  shells  or 
hard  parts  of  innumerable  marine  animals  of  different  kinds, 
some  entire,  some  fragmentary,  cemented  together  by  a  matrix 
of  very  finely  granular  carbonate  of  lime.  Foremost  amongst 
the  animal  remains  which  so  largely  compose  chalk  are  the 
shells  of  the  minute  creatures  which  will  be  subsequently 
cpoken  of  under  the  name  of  Foraminifera  (fig.  7),  and  which, 

in  spite  of  their  microscopic 
dimensions,  play  a  more  im- 
portant part  in  the  process  of 
lime-making  than  perhaps  any 
other  of  the  larger  inhabitants 
of  the  ocean. 

As  chalk  is  found  in  beds 
of  hundreds  of  feet  in  thick- 
ness, and  of  great  purity,  there 
was  long  felt  much  difficulty 
in  satisfactorily  accounting  for 
its  mode  of  formation  and  ori- 
gin. By  the  researches  of 
Carpenter,  Wyville  Thomson, 
Huxley,  Wallich,  and  others, 
it  has,  however,  been  shown 
that  there  is  now  forming,  in 
the  profound  depths  of  our 
great  oceans,  a  deposit  which 
is  in  all  essential  respects  identical  with  chalk,  and  which  is 
generally  known  as  the  "  Atlantic  ooze,"  from  its  having  been 
first  discovered  in  that  sea.  This  ooze  is  found  at  great 
depths  (5000  to  over  15,000  feet)  in  both  the  Atlantic  and 
Pacific,  covering  enormously  large  areas  of  the  sea-bottom, 
and  it  presents  itself  as  a  whitish-brown,  sticky,  impalpable  mud, 
very  like  greyish  chalk  when  dried.  Chemical  examination 
shows  that  the  ooze  is  composed  almost  wholly  of  carbonate  of 
lime,  and  microscopical  examination  proves  it  to  be  of  organic 
origin,  and  to  be  made  up  of  the  remains  of  living  beings. 
The  principal  forms  of  these  belong  to  the  Foraminifera,  and 
the  commonest  of  these  are  the  irregularly-chambered  shells  of 
Globigerina,  absolutely  indistinguishable  from  the  Globigerincz 
which  are  so  largely  present  in  the  chalk  (fig.  8).  Along  with 
these  occur  fragments  of  the  skeletons  of  other  larger  creatures, 


Fig.  7. — Section  of  Gravesend  Chalk, 
examined  by  transmitted  light  and  highly 
magnified.  Besides  the  entire  shells  of 
Globigerina,  Rotalia,  and  Textnlaria, 
numerous  detached  chambers  of  G.'obi- 
gerina  are  seen.  (Original.) 


THE   FOSSILIFEROUS    ROCKS. 


Fig.  8.— Organisms  in  the  Atlantic  Ooze. 
chiefly  Forarninifera  (Globigerina  and 
Textnlaria),  with  Polycystina  and  sponge- 
spicules ;  highly  magnified.  (Original.) 


and  a  certain  proportion  of  the  flinty  cases  of  minute  animal 
and  vegetable  organisms  (Polycystina  and  Diatoms').  Though 
many  of  the  minute  animals, 
the  hard  parts  of  which  form 
the  ooze,  undoubtedly  live  at 
or  near  the  surface  of  the  sea, 
others,  probably,  really  live 
near  the  bottom  ;  and  the  ooze 
itself  forms  a  congenial  home 
for  numerous  sponges,  sea- 
lilies,  and  other  marine  ani- 
mals which  flourish  at  great 
depths  in  the  sea.  There  is 
thus  established  an  intimate 
and  most  interesting  parallel- 
ism between  the  chalk  and 
the  ooze  of  modern  oceans. 
Both  are  formed  essentially  in 
the  same  way,  and  the  latter 
only  requires  consolidation  to  become  actually  converted  into 
chalk.  Both  are  fundamentally  organic  deposits,  apparently 
requiring  a  great  depth  of  water  for  their  accumulation,  and 
mainly  composed  of  the  remains  of  Foraminifera,  together 
with  the  entire  or  broken  skeletons  of  other  marine  animals  of 
greater  dimensions.  It  is  to  be  remembered,  however,  that  the 
ooze,  though  strictly  representative  of  the  chalk,  cannot  be 
said  in  any  proper  sense  to  be  actually  identical  with  the  for- 
mation so  called  by  geologists.  A  great  lapse  of  time  separates 
the  two,  and  though  composed  of  the  remains  of  representative 
classes  or  groups  of  animals,  it  is  only  in  the  case  of  the  lowly- 
organised  Globigerincz,  and  of  some  other  organisms  of  little 
higher  grade,  that  we  find  absolutely  the  same  kinds  or  species 
of  animals  in  both. 

Limestone,  like  chalk,  is  composed  of  carbonate  of  lime, 
sometimes  almost  pure,  but  more  commonly  with  a  greater  or 
less  intermixture  of  some  foreign  material,  such  as  alumina  or 
silica.  The  varieties  of  limestone  are  almost  innumerable, 
but  the  great  majority  can  be  clearly  proved  to  agree  with 
chalk  in  being  essentially  of  organic  origin,  and  in  being  more 
or  less  largely  composed  of  the  remains  of  living  beings.  In 
many  instances  the  organic  remains  which  compose  limestone 
are  so  large  as  to  be  readily  visible  to  the  naked  eye,  and  the 
rock  is  at  once  seen  to  be  nothing  more  than  an  agglomera- 
tion of  the  skeletons,  generally  fragmentary,  of  certain  marine 
.animals,  cemented  together  by  a  matrix  of  carbonate  of  lime. 


24  PRINCIPLES   OF   PALEONTOLOGY. 

This  is  the  case,  for  example,  with  the  so-called  "  Crinoidal 
Limestones  "  and  "  Encrinital  Marbles  "  with  which  the  geolo- 
gist is  so  familiar,  especially  as  occurring  in  great  beds  amongst 
the  older  formations  of  the  earth's  crust.  These  are  seen,  on 
weathered  or  broken  surfaces,  or  still  better  in  polished  slabs 
(hg.  9),  to  be  composed  more  or  less  exclusively  of  the  broken 


ida'  marble,  from  the  Carboniferous  limestone  of  Dent,  in  York- 
The  polished  surface  intersects  the  columns  of  the  Crinoids  at 
different  angles,  and  thus  gives  rise  to  varying  appearances.     (Original  ) 


V.g    9  —Slab  ot  L 
sh  re,  of  the  natural 


stems  and  detached  plates  of  sea-lilies  (Crinoids].  Similarly, 
other  limestones  are  composed  almost  entirely  of  the  skeletons 
of  corals ;  and  such  old  coralline  limestones  can  readily  be 
paralleled  by  formations  which  we  can  find  in  actual  course  of 
production  at  the  present  day.  We  only  need  to  transport 
ourselves  to  the  islands  of  the  Pacific,  to  the  West  Indies,  or 
to  the  Indian  Ocean,  to  find  great  masses  of  lime  formed  simi- 
larly by  living  corals,  and  well  known  to  every  one  under  the 
name  of  "coral-reefs."  Such  reefs  are  often  of  vast  extent, 
both  superficially  and  in  vertical  thickness,  and  they  fully  equal 
in  this  respect  any  of  the  coralline  limestones  of  bygone  ages. 
Again,  we  find  other  limestones  —  such  as  the  celebrated 
"  Nummulitic  Limestone"  (fig.  10),  which  sometimes  attains  a 
thickness  of  some  thousands  of  feet — which  are  almost  entirely 
made  up  of  the  shells  of  Foraminifera,  In  the  case  of  the 
"  Nummulitic  Limestone,"  just  mentioned,  these  shells  are  of 
large  size,  varying  from  the  size  of  a  split  pea  up  to  that  of  a 


THE   FOSSILIFEROUS   ROCKS.  25 

florin.     There  are,  however,  as  we  shall  see,  many  other  lime- 
stones, which  are  likewise  largely  made  up  of  Foramimferay 


Fig.  10. — Piece  of  Nummulitic  Limestone  from  the  Great  Pyramid. 
Of  the  natural  size.     (Original.) 

but  in  which  the  shells  are  very  much  more  minute,  and  would 
hardly  be  seen  at  all  without  the  microscope. 

We  may,  in  fact,  consider  that  the  great  agents  in  the  pro- 
duction of  limestones  in  past  ages  have  been  animals  belonging 
to  the  Crinoids,  the  Corals,  and  the  Foraminifera.  At  the  pre- 
sent day,  the  Crinoids  have  been  nearly  extinguished,  and  the 
few  known  survivors  seem  to  have  retired  to  great  depths  in 
the  ocean ;  but  the  two  latter  still  actively  carry  on  the  work 
of  lime-making,  the  former  being  very  largely  helped  in  their 
operations  by  certain  lime-producing  marine  plants  (Nullipores 
and  Corallines}.  We  have  to  remember,  however,  that  though 
the  limestones,  both  ancient  and  modern,  that  we  have  just 
spoken  of,  are  truly  organic,  they  are  not  necessarily  formed 
out  of  the  remains  of  animals  which  actually  lived  on  the 
precise  spot  where  we  now  find  the  limestone  itself.  We  may 
find  a  crinoidal  limestone,  which  we  can  show  to  have  been 
actually  formed  by  the  successive  growth  of  generations  of 
sea-lilies  in  place ;  but  we  shall  find  many  others  in  which  the 
rock  is  made  up  of  innumerable  fragments  of  the  skeletons  of 
these  creatures,  which  have  been  clearly  worn  and  rubbed  by 
the  sea-waves,  arid  which  have  been  mechanically  transported 
to  their  present  site.  In  the  same  way,  a  limestone  may  be 
shown  to  have  been  an  actual  coral-reef,  by  the  fact  that  we 
find  in  it  great  masses  of  coral,  growirg  in  their  natural  posi- 


26  PRINCIPLES  OF   PALEONTOLOGY. 

tion,  and  exhibiting  plain  proofs  that  they  were  simply  quietly 
buried  by  the  calcareous  sediment  as  they  grew ;  but  other 
limestones  may  contain  only  numerous  rolled  and  water- worn 
fragments  of  corals.  This  is  precisely  paralleled  by  what  we 
can  observe  in  our  existing  coral-reefs.  Parts  of  the  modern 
coral-islands  and  coral-reefs  are  really  made  up  of  corals,  dead 
or  alive,  which  actually  grew  on  the  spot  where  we  now  find 
them ;  but  other  parts  are  composed  of  a  limestone-rock 
("coral-rock"),  or  of  a  loose  sand  ("coral-sand"),  which  is 
organic  in  the  sense  that  it  is  composed  of  lime  formed  by 
living  beings,  but  which,  in  truth,  is  composed  of  fragments 
of  the  skeletons  of  these  living  beings,  mechanically  trans- 
ported and  heaped  together  by  the  sea.  To  take  another 
example  nearer  home,  we  may  find  great  accumulations  of 
calcareous  matter  formed  in  place,  by  the  growth  of  shell-fish, 
such  as  oysters  or  mussels  ;  but  we  can  also  find  equally  great 
accumulations  on  many  of  our  shores  in  the  form  of  "  shell- 
sand,"  which  is  equally  composed  of  the  shells  of  molluscs,  but 
which  is  formed  by  the  trituration  of  these  shells  by  the 
mechanical  power  of  the  sea- waves.  We  thus  see  that  though 
all  these  limestones  are  primarily  organic,  they  not  uncom- 
monly become  "mechanically-formed"  rocks  in  a  secondary 
sense,  the  materials  of  which  they  are  composed  being  formed 
by  living  beings,  but  having  been  mechanically  transported  to 
the  place  where  we  now  find  them. 

Many  limestones,  as  we  have  seen,  are  composed  of  large 
and  conspicuous  organic  remains,  such  as  strike  the  eye  at 
once.  Many  others,  however,  which  at  first  sight  appear  com- 
pact, more  or  less  crystalline,  and  nearly  devoid  of  traces  of 
life,  are  found,  when  properly  examined,  to  be  also  composed 
of  the  remains  of  various  organisms.  All  the  commoner  lime- 
stones, in  fact,  from  the  Lower  Silurian  period  onwards,  can 
be  easily  proved  to  be  thus  organic  rocks,  if  we  investigate 
weathered  or  polished  surfaces  with  a  lens,  or,  still  better,  if 
we  cut  thin  slices  of  the  rock  and  grind  these  down  till  they 
are  transparent.  When  thus  examined,  the  rock  is  usually 
found  to  be  composed  of  innumerable  entire  or  fragmentary 
fossils,  cemented  together  by  a  granular  or  crystalline  matrix 
of  carbonate  of  lime  (figs,  n  and  12).  When  the  matrix  is 
granular,  the  rock  is  precisely  similar  to  chalk,  except  that  it 
is  harder  and  less  earthy  in  texture,  whilst  the  fossils  are  only 
occasionally  referable  to  the  Foraminifera.  In  other  cases, 
the  matrix  is  more  or  less  crystalline,  and  when  this  crystallisa- 
tion has  been  carried  to  a  great  extent,  the  original  organic 
nature  of  the  rock  may  be  greatly  or  completely  obscured 


THE   FOSSILIFEROUS    ROCKS. 


thereby.     Thus,  in  limestones  which  have  been  greatly  altered 
or  "  metamorphosed"  by  the  combined  action  of  heat  and  pres- 


".  Fig.  n.  —  Section  of  Carboniferous 
Limestone  from  Spergen  Hill,  Indiana, 
U.S.,  showing  numerous  large-sized 
Forawiuifera  (Endothyra)  and  a  few 
oolitic  grains  ;  magnified.  (Original.) 


Fig  12. — Section  of  Coniston  Limestone 
(Lower  Silurian)  from  Keisley,  Westmore- 
land ;  magnified.  The  matrix  is  very  coarse- 
ly crystalline,  and  the  included  organic  re- 
mains are  chiefly  stems  of  Crinoids.  (Ori- 
ginal.) 


sure,  all  traces  of  organic  remains  become  annihilated,  and  the 
rock  becomes  completely  crystalline  throughout.  This,  for 
example,  is  the  case  with  the  ordinary  white  "statuary  marble," 
slices  of  which  exhibit  under  the  microscope  nothing  but  an 
aggregate  of  beautifully  transparent  crystals  of  carbonate  of 
lime,  without  the  smallest  traces  of  fossils.  There  are  also 
other  cases,  where  the  limestone  is  not  necessarily  highly 
crystalline,  and  where  no  metamorphic  action  in  the  strict 
sense  has  taken  place,  in  which,  nevertheless,  the  microscope 
fails  to  reveal  any  evidence  that  the  rock  is  organic.  Such 
cases  are  somewhat  obscure,  and  doubtless  depend  on  differ- 
ent causes  in  different  instances ;  but  they  do  not  affect  the 
important  generalisation  that  limestones  are  fundamentally  the 
product  of  the  operation  of  living  beings.  This  fact  remains 
certain  ;  and  when  we  consider  the  vast  superficial  extent 
occupied  by  calcareous  deposits,  and  the  enormous  collective 
thickness  of  these,  the  mind  cannot  fail  to  be  impressed  with 
the  immensity  of  the  period  demanded  for  the  formation  of 
these  by  the  agency  of  such  humble  and  often  microscopic 
creatures  as  Corals,  Sea-lilies,  Foraminifers,  and  Shell  fish. 

Amongst  the  numerous  varieties  of  limestone,  a  few  are  of 
such  interest  as  to  deserve  a  brief  notice.  Magnesian  limestone- 
or  dolomite,  differs  from  ordinary  limestone  in  containing  a  cer- 
tain proportion  of  carbonate  of  magnesia  along  with  the  carbon, 
ate  of  lime.  The  typical  dolomites  contain  a  large  proportion  of 


28  PRINCIPLES   OF   PALEONTOLOGY. 

carbonate  of  magnesia,  and  are  highly  crystalline.  The  ordi- 
nary magnesian  limestones  (such  as  those  of  Durham  in  the 
Permian  series,  and  the  Guelph  Limestones  of  North  America 
in  the  Silurian  series)  are  generally  of  a  yellowish,  buff,  or 
brown  colour,  with  a  crystalline  or  pearly  aspect,  effervescing 
with  acid  much  less  freely  than  ordinary  limestone,  exhibiting 
numerous  cavities  from  which  fossils  have  been  dissolved  out, 
and  often  assuming  the  most  varied  and  singular  forms  in  con- 
sequence of  what  is  called  "  concretionary  action."  Examina- 
tion with  the  microscope  shows  that  these  limestones  are 
composed  of  an  aggregate  of  minute  but  perfectly  distinct 
crystals,  but  that  minute  organisms  of  different  kinds  or 
fragments  of  larger  fossils,  are  often  present  as  well.  Other 
magnesian  limestones,  again,  exhibit  no  striking  external  pecu- 
liarities by  which  the  presence  of  magnesia  would  be  readily 
recognised,  and  though  the  base  of  the  rock  is  crystalline,  thry 
are  replete  with  the  remains  of  organised  beings.  Thus  many 
of  the  magnesian  limestones  of  the  Carboniferous  series  of  the 
North  of  England  are  very  like  ordinary  limestone  to  look  at, 
though  effervescing  less  freely  with  acids,  and  the  microscope 
proves  them  to  be  charged  with  the  remains  of  Foraminifera 
and  other  minute  organisms. 

Marbles  are  of  various  kinds,  all  limestones  which  are  suffi- 
ciently hard  and  compact  to  take  a  high  polish  going  by  this 
name.  Statuary  marble,  and  most  of  the  celebrated  foreign 
marbles,  are  "  metamorphic  "  rocks,  of  a  highly  crystalline 
nature,  and  having  all  traces  of  their  primitive  organic  struc- 
ture obliterated.  Many  other  marbles,  however,  differ  from 
ordinary  limestone  simply  in  the  matter  of  density.  Thus, 
many  marbles  (such  as  Derbyshire  marble)  are  simply  "  cri- 
noidal  limestones"  (fig.  9);  whilst  various  other  British 
marbles  exhibit  innumerable  organic  remains  under  the  mi- 
croscope. Black  marbles  owe  their  colour  to  the  presence  of 
very  minute  particles  of  carbonaceous  matter,  in  some  cases 
at  any  rate;  and  they  may  either  be  metamorphic,  or  they 
may  be  charged  with  minute  fossils  such  as  Foraminifera  (e.g., 
the  black  limestones  of  Ireland,  and  the  black  marble  of  Dent, 
in  Yorkshire). 

"Oolitic"  limestones,  or  "  oolites"'  as  they  are  often  called, 
are  of  interest  both  to  the  palaeontologist  and  geologist.  The 
peculiar  structure  to  which  they  owe  their  name  is  that  the 
rock  is  more  or  less  entirely  composed  of  spheroidal  or  oval 
grains,  which  vary  in  size  from  the  head  of  a  small  pin  or  less 
up  to  the  size  of  a  pea.  and  which  maybe  in  almost  immediate 
contact  with  one  another,  or  may  be  cemented  together  by  a 


THE   FOSSILIFEROUS   ROCKS.  29 

more  or  less  abundant  calcareous  matrix.  When  the  grains 
are  pretty  nearly  spherical  and  are  in  tolerably  close  contact, 
the  rock  looks  very  like  the  roe  of  a  fish,  and  the  name  of 
*•  oolite  "  or  "  egg-stone  "  is  in  allusion  to  this.  When  the 
grains  are  of  the  size  of  peas  or  upwards,  the  rock  is  often 
called  a  "pisolite"  (Lat.  pisum,  a  pea).  Limestones  having 
this  peculiar  structure  are  especially  abundant  in  the  Jurassic 
formation,  which  is  often  called  the  "  Oolitic  series  "  for  this 
reason;  but  essentially  similar  limestones  occur  not  uncom- 
monly in  the  Silurian,  Devonian,  and  Carboniferous  forma- 
tions, and,  indeed,  in  almost  all  rock-groups  in  which  limestones 
are  largely  developed.  Whatever  may  be  the  age  of  the  for- 
mation in  which  they  occur,  and  whatever  may  be  the  size  of 
their  component  "  eggs,"  the  structure  of  colitic  limestones  is 
fundamentally  the  same.  All  the  ordinary  oolitic  limestones, 
namely,  consist  of  little  spherical  or  ovoid  "  concretions,"  as 
they  are  termed,  cemented  together  by  a  larger  or  smaller 
amount  of  crystalline  carbonate  of  lime,  together,  in  many 
instances,  with  numerous  organic  remains  of  different  kinds 
(fig.  13).  When  examined  in  polished  slabs,  or  in  thin  sec- 
tions prepared  for  the  micro- 
scope, each  of  these  little  con- 
cretions is  seen  to  consist  of 
numerous  concentric  coats  of 
carbonate  of  lime,  which  some- 
times simply  surround  an  ima- 
ginary centre,  but  which,  more 
commonly,  have  been  suc- 
cessively deposited  round 
some  foreign  body,  such  as  a 
little  crystal  of  quartz,  a  clus- 
ter of  sand  grains,  or  a  minute 
shell.  In  other  cases,  as  in 

SOme  Of   the  beds    Of  the  Car-  Fig-     13.  —  Slice     of    oolitic     lirrestone 

IT  v  ,1  from    the    Jurassic    series  (Coral    Rag)    of 

bomferOUS     limestone     111     the       Weymouth ;  magnified.     (Original.) 

North  of  England,  where  the 

limestone  is  highly  "arenaceous,"  there  is  a  modification  of  the 
oolitic  structure.  Microscopic  sections  of  these  sandy  lime- 
stones (fig.  14)  show  numerous  generally  angular  or  oval  grains 
of  silica  or  flint,  each  of  which  is  commonly  surrounded  by  a 
thin  coating  of  carbonate  of  lime,  or  sometimes  by  several  such 
coats,  the  whole  being  cemented  together  along  with  the  shells 
of  Foraminifera  and  other  minute  fossils  by  a  matrix  of  crystal- 
line calcite.  As  compared  with  typical  oolites,  the  concretions 
in  these  limestones  are  usually  much  more  irregular  in  shape, 
4 


PRINCIPLES   OF   PALEONTOLOGY. 


Fig.  14. — Slice  of  arenaceous  and 
oolitic  limestone  from  the  Carbonifer- 
ous series  of  Shap,  Westmoreland  ;  mag- 
nified. The  section  also  exhibits  Fora- 
mini/era,  and  other  minute  fossils.  (Ori- 
ginal.) 


often  lengthened  out  and  almost  cylindrical,  at  other  times 
angular,  the  central  nucleus  being  of  large  size,  and  the  sur- 
rounding envelope  of  lime  be- 
ing very  thin,  and  often  exhib- 
iting no  concentric  structure. 
In  both  these  and  the  ordinary 
oolites,  the  structure  is  funda- 
mentally the  same.  Both  have 
been  formed  in  a  sea,  probably 
of  no  great  depth,  the  waters 
of  which  were  charged  with 
carbonate  of  lime  in  solution, 
whilst  the  bottom  was  formed 
of  sand  intermixed  with  minute 
shells  and  fragments  of  the 
skeletons  of  larger  marine  ani- 
mals. The  excess  of  lime  in 
the  sea-water  was  precipitated 
round  the  sand-grains,  or  round 
the  smaller  shells,  as  so  many 
nuclei,  and  this  precipitation  must  often  have  taken  place  time 
after  time,  so  as  to  give  rise  to  the  concentric  structure  so  char- 
acteristic of  oolitic  concretions.  Finally,  the  oolitic  grains  thus 
produced  were  cemented  together  by  a  further  precipitation  of 
crystalline  carbonate  of  lime  from  the  waters  of  the  ocean. 

Phosphate  of  Lime  is  another  lime-salt,  which  is  of  interest 
to  the  palaeontologist.  It  does  not  occur  largely  in  the  strati- 
fied series,  but  it  is  found  in  considerable  beds  *  in  the 
Laurentian  formation,  and  less  abundantly  in  some  later  rock- 
groups,  whilst  it  occurs  abundantly  in  the  form  of  nodules  in 
parts  of  the  Cretaceous  (Upper  Greensand)  and  Tertiary 
deposits.  Phosphate  of  lime  forms  the  larger  proportion  of 
the  earthy  matters  of  the  bones  of  Vertebrate  animals,  and  also 
occurs  in  less  amount  in  the  skeletons  of  certain  of  the  Inver- 
tebrates (e.g.,  Crustacea).  It  is,  indeed,  perhaps  more  dis- 
tinctively than  carbonate  of  lime,  an  organic  compound  ;  and 
though  the  formation  of  many  known  deposits  of  phosphate  of 

*  Apart  from  the  occurrence  of  phosphate  of  lime  in  actual  beds  in  the 
stratified  rocks,  as  in  the  Laurentian  and  Silurian  series,  this  salt  may  also 
occur  disseminated  through  the  rock,  when  it  can  only  be  detected  by 
chemical  analysis.  It  is  interesting  to  note  that  Dr  Hicks  has  recently 
proved  the  occurrence  of  phosphate  of  lime  in  this  disseminated  form  in 
rocks  as  old  as  the  Cambrian,  and  that  in  quantity  quite  equal  to  what  is 
generally  found  to  be  present  in  the  later  fossiliferous  rocks.  This  affords 
a  chemical  proof  that  animal  life  flourished  abundantly  in  the  Cambrian 


THE   FOSSILIFEROUS    ROCKS.  31 

lime  cannot  be  positively  shown  to  be  connected  with  the 
previous  operation  of  living  beings,  there  is  room  for  doubt 
whether  this  salt  is  not  in  reality  always  primarily  a  product 
of  vital  action.  The  phosphatic  nodules  of  the  Upper  Green- 
sand  are  erroneously  called  "  coprolites,"  from  the  belief 
originally  entertained  that  they  were  the  droppings  or  fossilised 
excrements  of  extinct  animals  ;  and  though  this  is  not  the  case, 
there  can  be  little  doubt  but  that  the  phosphate  of  lime  which 
they  contain  is  in  this  instance  of  organic  origin.*  It  appears, 
in  fact,  that  decaying  animal  matter  has  a  singular  power  of 
determining  the  precipitation  around  it  of  mineral  salts  dis- 
solved in  water.  Thus,  when  any  animal  bodies  are  undergo- 
ing decay  at  the  bottom  of  the  sea,  they  have  a  tendency  to 
cause  the  precipitation  from  the  surrounding  water  of  any 
mineral  matters  which  may  be  dissolved  in  it ;  and  the  organic 
body  thus  becomes  a  centre  round  which  the  mineral  matters 
in  question  are  deposited  in  the  form  of  a  "  concretion "  or 
"  nodule."  The  phosphatic  nodules  in  question  were  formed 
in  a  sea  in  which  phosphate  of  lime,  derived  from  the  destruc- 
tion of  animal  skeletons,  was  held  largely  in  solution  ;  and  a 
precipitation  of  it  took  place  round  any  body,  such  as  a  decay- 
ing animal  substance,  which  happened  to  be  lying  on  the  sea- 
bottom,  and  which  offered  itself  as  a  favourable  nucleus.  In 
the  same  way  we  may  explain  the  formation  of  the  calcareous 
nodules,  known  as  "septaria"  or  "cement  stones,"  which 
occur  so  commonly  in  the  London  Clay  and  Kimmeridge 
Clay,  and  in  which  the  principal  ingredient  is  carbonate  of 
lime.  A  similar  origin  is  to  be  ascribed  to  the  nodules  of 
clay  iron-stone  (impure  carbonate  of  iron)  which  occur  so 
abundantly  in  the  shales  of  the  Carboniferous  series  and  in 
other  argillaceous  deposits ;  and  a  parallel  modern  example  is 
to  be  found  in  the  nodules  of  manganese,  which  were  found 
by  Sir  Wyville  Thomson,  in  the  Challenger,  to  be  so  numer- 
ously scattered  over  the  floor  of  the  Pacific  at  great  depths. 
In  accordance  with  this  mode  of  origin,  it  is  exceedingly 
common  to  find  in  the  centre  of  all  these  nodules,  both  old 
and  new,  some  organic  body,  such  as  a  bone,  a  shell,  or  a 
tooth,  which  acted  as  the  original  nucleus  of  precipitation,  and 

*  It  has  been  maintained,  indeed,  that  the  phosphatic  nodules  so  largely 
worked  for  agricultural  purposes,  are  in  themselves  actual  organic  bodies 
or  true  fossils.  In  a  few  cases  this  admits  of  demonstration,  as  it  can  be 
shown  that  the  nodule  is  simply  an  organism  (such  as  a  sponge)  infiltrated 
with  phosphate  of  lime  (Sollas)  ;  but  there  are  many  other  cases  in  which 
no  actual  structure  has  yet  been  shown  to  exist,  and  as  to  the  true  origin 
of  which  it  would  be  hazardous  to  offer  a  positive  opinion. 


32  PRINCIPLES   OF   PALEONTOLOGY. 

was  thus  preserved  in  a  shroud  of  mineral  matter.  Many 
nodules,  it  is  true,  show  no  such  nucleus ;  but  it  has  been 
affirmed  that  all  of  them  can  be  shown,  by  appropriate 
microscopical  investigation,  to  have  been  formed  round  an 
original  organic  body  to  begin  with  (Hawkins  Johnson). 

The  last  lime-salt  which  need  be  mentioned  is  gypsum,  or 
sulphate  of  lime.  This  substance,  apart  from  other  modes  of 
occurrence,  is  not  uncommonly  found  interstratified  with  the 
ordinary  sedimentary  rocks,  in  the  form  of  more  or  less  irregu- 
lar beds;  and  in  these  cases  it  has  a  palaeontological  import- 
ance, as  occasionally  yielding  well-preserved  fossils.  Whilst 
its  exact  mode  of  origin  is  uncertain,  it  cannot  be  regarded  as 
in  itself  an  organic  rock,  though  clearly  the  product  of  chemical 
action.  To  look  at,  it  is  usually  a  whitish  or  yellowish-white 
rock,  as  coarsely  crystalline  as  loaf-sugar,  or  more  so;  and  the 
microscope  shows  it  to  be  composed  entirely  of  crystals  of 
sulphate  of  lime. 

We  have  seen  that  the  calcareous  or  lime-containing  rocks 
are  the  most  important  of  the  group  of  organic  deposits;  whilst 
the  siliceous  or  flint-containing  rocks  may  be  regarded  as  the 
most  important,  most  typical,  and  most  generally  distributed 
of  the  mechanically-formed  rocks.  We  have,  however,  now 
briefly  to  consider  certain  deposits  which  are  more  or  less 
completely  formed  of  flint;  but  which,  nevertheless,  are  essen- 
tially organic  in  their  origin. 

Flint  or  silex,  hard  and  intractable  as  it  is,  is  nevertheless 
capable  of  solution  in  water  to  a  certain  extent,  and  even  of 
assuming,  under  certain  circumstances,  a  gelatinous  or  viscous 
condition.  Hence,  some  hot -springs  are  impregnated  with 
silica  to  a  considerable  extent ;  it  is  present  in  small  quantity 
in  sea-water ;  and  there  is  reason  to  believe  that  a  minute  pro- 
portion must  very  generally  be  present  in  all  bodies  of  fresh 
water  as  well.  It  is  from  this  silica  dissolved  in  the  water  that 
many  animals  and  some  plants  are  enabled  to  construct  for 
themselves  flinty  skeletons;  and  we  find  that  these  animals  and 
plants  are  and  have  been  sufficiently  numerous  to  give  rise  to 
very  considerable  deposits  of  siliceous  matter  by  the  mere 
accumulation  of  their  skeletons.  Amongst  the  animals  which 
require  special  mention  in  this  connection  are  the  microscopic 
organisms  which  are  known  to  the  naturalist  as  Polycystina. 
These  little  creatures  are  of  the  lowest  possible  grade  of  organ- 
isation, very  closely  related  to  the  animals  which  we  have  pre- 
viously spoken  of  as  fbraminifera,\)U\.  differing  in  the  fact  that 
they  secrete  a  shell  or  skeleton  composed  of  flint  instead  of 
lime.  The  Polycystina  occur  abundantly  in  our  present  seas; 


THE   FOSSILIFEROUS   ROCKS. 


33 


and  their  shells  are  present  in  some  numbers  in  the  ooze  which 
is  found  at  great  depths  in  the  Atlantic  and  Pacific  oceans, 
being  easily  recognised  by  their  exquisite  shape,  their  glassy 
transparency,  the  general  presence  of  longer  or  shorter  spines, 
and  the  sieve-like  perforations  in  the  walls.  Both  in  Barbadoes 
and  in  the  Nicobar  islands  occur  geological  formations  which 
are  composed  of  the  flinty  skeletons  of  these  microscopic 
animals ;  the  deposit  in  the  former  locality  attaining  a  great 
thickness,  and  having  been  long  known  to  workers  with  the 
microscope  under  the  name  of  "  Barbadoes  earth  "  (fig.  15). 

In  addition  to  flint -producing  animals,  we  have  also  the 
great  group  of  fresh -water  and  marine   microscopic   plants 


Fig.    15. — Shells   of    Po7ycysthia   from  Fig.  16. — Cases  of  Diatoms  in  the  Ricli- 

"  Barbadoes  earth;"  greatly  magniiied.  mond  "Infusorial  earth;"  highly  magni- 
(Original.)  fied.  (Original.) 

known  as  Diatoms,  which  likewise  secrete  a  siliceous  skeleton, 
often  of  great  beauty.  The  skeletons  of  Diatoms  are  found 
abundantly  at  the  present  day  in  lake-deposits,  guano,  the  silt 
of  estuaries,  and  in  the  mud  which  covers  many  parts  of  the 
sea-bottom;  they  have  been  detected  in  strata  of  great  age; 
and  in  spite  of  their  microscopic  dimensions,  they  have  not  un- 
commonly accumulated  to  form  deposits  of  great  thickness, 
and  of  considerable  superficial  extent.  Thus  the  celebrated 
deposit  of  "tripoli"  ("  Polir-schiefer ")  of  Bohemia,  largely 
worked  as  polishing-powder,  is  composed  wholly,  or  almost 
wholly,  of  the  flinty  cases  of  Diatoms,  of  which  it  is  calculated 
that  no  less  than  forty-one  thousand  millions  go  to  make  up  a 
single  cubic  inch  of  the  stone.  Another  celebrated  deposit  is 
the  so-called  "  Infusorial  earth "  of  Richmond  in  Virginia, 
where  there  is  a  stratum  in  places  thirty  feet  thick,  composed 
almost  entirely  of  the  microscopic  shells  of  Diatoms. 

Nodules  or  layers  of  flint,  or  the  impure  variety  of  flint 


34  PRINCIPLES   OF   PALEONTOLOGY. 

known  as  chert,  are  found  in  limestones  of  almost  all  ages  from 
the  Silurian  upwards ;  but  they  are  especially  abundant  in  the 
chalk.  When  these  flints  are  examined  in  thin  and  trans- 
parent slices  under  the  microscope,  or  in  polished  sections, 
they  are  found  to  contain  an  abundance  of  minute  organic 
bodies — such  as  Foraminifera,  sponge-spicules,  &c. — embedded 
in  a  siliceous  basis.  In  many  instances  the  flint  contains 
larger  organisms — such  as  a  Sponge  or  a  Sea-urchin.  As  the 
flint  has  completely  surrounded  and  infiltrated  the  fossils  which 
it  contains,  it  is  obvious  that  it  must  have  been  deposited  from 
sea-water  in  a  gelatinous  condition,  and  subsequently  have 
hardened.  That  silica  is  capable  of  assuming  this  viscous  and 
soluble  condition  is  known ;  and  the  formation  of  flint  may 
therefore  be  regarded  as  due  to  the  separation  of  silica  from 
the  sea-water  and  its  deposition  round  some  organic  body  in  a 
sta'te  of  chemical  change  or  decay,  just  as  nodules  of  phos- 
phate of  lime  or  carbonate  of  iron  are  produced.  The  exist- 
ence of  numerous  organic  bodies  in  flint  has  long  been  known; 
but  it  should  be  added  that  a  recent  observer  (Mr  Hawkins 
Johnson)  asserts  that  the  existence  of  an  organic  structure  can 
be  demonstrated  by  suitable  methods  of  treatment,  even  in  the 
actual  matrix  or  basis  of  the  flint* 

In  addition  to  deposits  formed  of  flint  itself,  there  are  other 
siliceous  deposits  formed  by  certain  silicates,  and  also  of 
organic  origin.  It  has  been  shown,  namely — by  observations 
carried  out  in  our  present  seas — that  the  shells  of  Foraminifera 
are  liable  to  become  completely  infiltrated  by  silicates  (such 
as  "  glauconite,"  or  silicate  of  iron  and  potash).  Should  the 
actual  calcareous  shell  become  dissolved  away  subsequent  to 
this  infiltration — as  is  also  liable  to  occur — then,  in  place  of 
the  shells  of  the  Foraminifera,  we  get  a  corresponding  number 
of  green  sandy  grains  of  glauconite,  each  grain  being  the  cast 
of  a  single  shell.  It  has  thus  been  shown  that  the  green  sand 
found  covering  the  sea-bottom  in  certain  localities  (as  found 
by  the  Challenger  expedition  along  the  line  of  the  Agulhas 
current)  is  really  organic,  and  is  composed  of  casts  of  the 
shells  of  Foraminifera.  Long  before  these  observations  had 
been  made,  it  had  been  shown  by  Professor  Ehrenberg  that 
the  green  sands  of  various  geological  formations  are  composed 
mainly  of  the  internal  casts  of  the  shells  of  Foraminifera  ;  and 

*  It  has  been  asserted  that  the  flints  of  the  chalk  are  merely  fossil 
sponges.  No  explanation  of  the  origin  of  flint,  however,  can  be  satisfac- 
tory, unless  it  embraces  the  origin  of  chert  in  almost  all  great  limestones 
from  the  Silurian  upwards,  as  well  as  the  common  phenomenon  of  the 
silicification  of  organic  bodies  (such  as  corals  and  shells)  which  are  known 
with  certainty  to  have  been  originally  calcareous. 


THE    FOSSILIFEROUS    ROCKS.  35 

we  have  thus  another  and  a  very  interesting  example  how  rock- 
deposits  of  considerable  extent  and  of  geological  importance 
can  be  built  up  by  the  operation  of  the  minutest  living  beings. 

As  regards  argillaceous  deposits,  containing  alumina  or  clay 
as  their  essential  ingredient,  it  cannot  be  said  that  any  of 
these  have  been  actually  shown  to  be  of  organic  origin.  A 
recent  observation  by  Sir  Wyville  Thomson  would,  however, 
render  it  not  improbable  that  some  of  the  great  argillaceous 
accumulations  of  past  geological  periods  maybe  really  organic. 
This  distinguished  observer,  during  the  cruise  of  the  Chal- 
lenger, showed  that  the  calcareous  ooze  which  has  been 
already  spoken  of  as  covering  large  areas  of  the  floor  of  the 
Atlantic  and  Pacific  at  great  depths,  and  which  consists  almost 
wholly  of  the  shells  of  Foraminifera^  gave  place  at  still  greater 
depths  to  a  red  ooze  consisting  of  impalpable  clayey  mud, 
coloured,  by  oxide  of  iron,  and  devoid  of  traces  of  organic 
bodies.  As  the  existence  of  this  widely-diffused  red  ooze,  in 
mid-ocean,  and  at  such  great  depths,  cannot  be  explained  on 
the  supposition  that  it  is  a  sediment  brought  down  into  the 
sea  by  rivers,  Sir  Wyville  Thomson  came  to  the  conclusion 
that  it  was  probably  formed  by  the  action  of  the  sea-water 
upon  the  shells  of  Foraminifera.  These  shells,  though  mainly 
consisting  of  lime,  also  contain  a  certain  proportion  of  alumina, 
the  former  being  soluble  in  the  carbonic  acid  dissolved  in  the 
sea-water,  whilst  the  latter  is  insoluble.  There  would  further 
appear  to  be  grounds  for  believing  that  the  solvent  power  of 
the  sea -water  over  lime  is  considerably  increased  at  great 
depths.  If,  therefore,  we  suppose  the  shells  of  Foraminifera 
to  be  in  course  of  deposition  over  the  floor  of  the  Pacific,  at 
certain  depths  they  would  remain  unchanged,  and  would  ac- 
cumulate to  form  a  calcareous  ooze;  but  at  greater  depths  they 
would  be  acted  upon  by  the  water,  their  lime  would  be  dis- 
solved out,  their  form  would  disappear,  and  we  should  simply 
have  left  the  small  amount  of  alumina  which  they  previously 
contained.  In  process  of  time  this  alumina  would  accumulate 
to  form  a  bed  of  clay;  and  as  this  clay  had  been  directly 
derived  from  the  decomposition  of  the  shells  of  animals,  it 
would  be  fairly  entitled  to  be  considered  an  organic  deposit. 
Though  not  finally  established,  the  hypothesis  of  Sir  Wyville 
Thomson  on  this  subject  is  of  the  greatest  interest  to  the  palae- 
ontologist, as  possibly  serving  to  explain  the  occurrence,  espe- 
cially in  the  older  formations,  of  great  deposits  of  argillaceous 
matter  which  are  entirely  destitute  of  traces  of  life. 

It  only  remains,  in  this  connection,  to  shortly  consider  the 
rock-deposits  in  which  carbon  is  found  to  be  present  in  greater 


36  PRINCIPLES   OF   PALAEONTOLOGY. 

or  less  quantity.  In  the  great  majority  of  cases  where  rocks 
are  found  to  contain  carbon  or  carbonaceous  matter,  it  can  be 
stated  with  certainty  that  this  substance  is  of  organic  origin, 
though  it  is  not  necessarily  derived  from  vegetables.  Carbon 
derived  from  the  decomposition  of  animal  bodies  is  not  uncom- 
mon ;  though  it  never  occurs  in  such  quantity  from  this  source 
as  it  may  do  when  it  is  derived  from  plants.  Thus,  many 
limestones  are  more  or  less  highly  bituminous ;  the  celebrated 
siliceous  flags  or  so-called  "  bituminous  schists  "  of  Caithness 
are  impregnated  with  oily  matter  apparently  derived  from  the 
decomposition  of  the  numerous  fishes  embedded  in  them  ; 
Silurian  shales  containing  Graptolites,  but  destitute  of  plants, 
are  not  uncommonly  "anthracitic,"  and  contain  a  small  per- 
centage of  carbon  derived  from  the  decay  of  these  zoophytes  ; 
whilst  the  petroleum  so  largely  worked  in  North  America  has 
not  improbably  an  animal  origin.  That  the  fatty  compounds 
present  in  animal  bodies  should  more  or  less  extensively  im- 
pregnate fossiliferous  rock-masses,  is  only  what  might  be  ex- 
pected ;  but  the  great  bulk  of  the  carbon  which  exists  stored 
up  in  the  earth's  crust  is  derived  from  plants  ;  and  the  form  in 
which  it  principally  presents  itself  is  that  of  coal.  We  shall 
have  to  speak  again,  and  at  greater  length,  of  coal,  and  it  is 
sufficient  to  say  here  that  all  the  true  coals,  anthracites,  and 
lignites,  are  of  organic  origin,  and  consist  principally  of  the 
remains  of  plants  in  a  more  or  less  altered  condition.  The 
bituminous  shales  which  are  found  so  commonly  associated 
with  beds  of  coal  also  derive  their  carbon  primarily  from 
plants ;  and  the  same  is  certainly,  or  probably,  the  case  with 
similar  shales  which  are  known  to  occur  in  formations  younger 
than  the  Carboniferous.  Lastly,  carbon  may  occur  as  a  con- 
spicuous constituent  of  rock-masses  in  the  form  of  graphite  or 
black-lead.  In  this  form,  it  occurs  in  the  shape  of  detached 
scales,  of  veins  or  strings,  or  sometimes  of  regular  layers;* 
and  there  can  be  little  doubt  that  in  many  instances  it  has 
an  organic  origin,  though  this  is  not  capable  of  direct  proof. 
When  present,  at  any  rate,  in  quantity,  and  in  the  form  of  layers 
associated  with  stratified  rocks,  as  is  often  the  case  in  the  Lau- 
rentian  formation,  there  can  be  little  hesitation  in  regarding  it 
as  of  vegetable  origin,  and  as  an  altered  coal. 

*  In  the  Huronian  formation  at  Steel  River,  on  the  north  shore  of  Lake 
Superior,  there  exists  a  bed  of  carbonaceous  matter  which  is  regularly  in- 
terstratified  with  the  surrounding  rocks,  and  has  a  thickness  of  from  30  to 
40  feet.  This  bed  is  shown  by  chemical  analysis  to  contain  about  50  per 
cent  of  carbon,  partly  in  the  form  of  graphite,  partly  in  the  form  of  anthra- 
cite ;  and  there  can  be  little  doubt  but  that  it  is  really  a  stratum  of  "meta- 
morphic  "  coal. 


CHRONOLOGICAL  SUCCESSION.  37 


CHAPTER    III. 

CHRONOLOGICAL  SUCCESSION  OF  THE 
FOSSILIFEROUS  ROCKS. 

The  physical  geologist,  who  deals  with  rocks  simply  as  rocks, 
and  who  does  not  necessarily  trouble  himself  about  what  fossils 
they  may  contain,  finds  that  the  stratified  deposits  which  form 
so  large  a  portion  of  the  visible  part  of  the  earth's  crust  are 
not  promiscuously  heaped  together,  but  that  they  have  a  cer- 
tain definite  arrangement.  In  each  country  that  he  examines, 
he  finds  that  certain  groups  of  strata  lie  above  certain  other 
groups  ;  and  in  comparing  different  countries  with  one  another, 
he  finds  that,  in  the  main,  the  same  groups  of  rocks  are  always 
found  in  the  same  relative  position  to  each  other.  It  is  pos- 
sible, therefore,  for  the  physical  geologist  to  arrange  the  known 
stratified  rocks  into  a  successive  series  of  groups,  or  "  forma- 
tions," having  a  certain  definite  order.  The  establishment  of 
this  physical  order  amongst  the  rocks  introduces,  however,  at 
once  the  element  of  time,  and  the  physical  succession  of  the 
strata  can  be  converted  directly  into  a  historical  or  chronologi- 
cal succession.  This  is  obvious,  when  we  reflect  that  any  bed 
or  set  of  beds  of  sedimentary  origin  is  clearly  and  necessarily 
younger  than  all  the  strata  upon  which  it  rests,  and  older  than 
all  those  by  which  it  is  surmounted. 

It  is  possible,  then,  by  an  appeal  to  the  rocks  alone,  to  de- 
termine in  each  country  the  general  physical  succession  of  the 
strata,  and  this  "  stratigraphical "  arrangement,  when  once  de- 
termined, gives  us  the  relative  ages  of  the  successive  groups. 
The  task,  however,  of  the  physical  geologist  in  this  matter  is 
immensely  lightened  when  he  calls  in  palaeontology  to  his  aid, 
and  studies  the  evidence  of  the  fossils  embedded  in  the  rocks. 
Not  only  is  it  thus  much  easier  to  determine  the  order  of  suc- 
cession of  the  strata  in  any  given  region,  but  it  becomes  now 
for  the  first  time  possible  to  compare,  with  certainty  and  pre- 
cision, the  order  of  succession  in  one  region  with  that  which 
exists  in  other  regions  far  distant.  The  value  of  fossils  as  tests 
of  the  relative  ages  of  the  sedimentary  rocks  depends  on  the 
fact  that  they  are  not  indefinitely  or  promiscuously  scattered 
through  the  crust  of  the  earth, — as  it  is  conceivable  that  they 
might  be.  On  the  contrary,  the  first  and  most  firmly  estab- 
lished law  of  Palaeontology  is,  that  particular  kinds  of  fossils 


3#  PRINCIPLES  OF   PALAEONTOLOGY. 

are  confined  to  particular  rocks,  and  particular  groups  of  fossils 
are  confined  to  particular  groups  of  rocks.  Fossils,  then,  are 
distinctive  of  the  rocks  in  which  they  are  found — much  more 
distinctive,  in  fact,  than  the  mere  mineral  character  of  the  rock 
can  be,  for  that  commonly  changes  as  a  formation  is  traced 
from  one  region  to  another,  whilst  the  fossils  remain  unaltered. 
It  would  therefore  be  quite  possible  for  the  palaeontologist, 
by  an  appeal  to  the  fossils  alone,  to  arrange  the  series  of  sedi- 
mentary deposits  into  a  pile  of  strata  having  a  certain  definite 
order.  Not  only  would  this  be  possible,  but  it  would  be  found 
— if  sufficient  knowledge  had  been  brought  to  bear  on  both 
sides — that  the  palaeontological  arrangement  of  the  strata  would 
coincide  in  its  details  with  the  stratigraphical  or  physical 
arrangement. 

Happily  for  science,  there  is  no  such  division  between  the 
palaeontologist  and  the  physical  geologist  as  here  supposed ; 
but  by  the  combined  researches  of  the  two,  it  has  been  found 
possible  to  divide  the  entire  series  of  stratified  deposits  into  a 
number  of  definite  rock  -groups  or  formations,  which  have  a 
recognised  order  of  succession,  and  each  of  which  is  charac- 
terised by  possessing  an  assemblage  of  organic  remains  which 
do  not  occur  in  association  in  any  other  formation.  Such  an 
assemblage  of  fossils,  characteristic  of  any  given  formation,  re- 
presents the  life  of  the  particular  period  in  which  the  formation 
was  deposited.  In  this  way  the  past  history  of  the  earth 
becomes  divided  into  a  series  of  successive  life-periods,  each  of 
which  corresponds  with  the  deposition  of  a  particular  forma- 
tion or  group  of  strata. 

Whilst  particular  assemblages  of  organic  forms  characterise 
particular  groups  of  rocks,  it  may  be  further  said  that,  in  a 
general  way,  each  subdivision  of  each  formation  has  its  own 
peculiar  fossils,  by  which  it  may  be  recognised  by  a  skilled 
worker  in  Palaeontology.  Whenever,  for  instance,  we  meet 
with  examples  of  the  fossils  which  are  known  as  Graptolites,  we 
may  be  sure  that  we  are  dealing  with  Silurian  rocks  (leaving 
out  of  sight  one  or  two  forms  doubtfully  referred  to  this  family). 
We  may,  however,  go  much  farther  than  this  with  perfect 
safety.  If  the  Graptolites  belong  to  certain  genera,  we  may 
be  quite  certain  that  we  are  dealing  with  Lower  Silurian  rocks. 
Furthermore,  if  certain  special  forms  are  present,  we  may  be 
even  able  to  say  to  what  exact  subdivision  of  the  Lower  Silu- 
rian series  they  belong. 

As  regards  particular  fossils,  however,  or  even  particular 
classes  of  fossils,  conclusions  of  this  nature  require  to  be  accom- 
panied by  a  tacit  but  well-understood  reservation.  So  far  as 


CHRONOLOGICAL   SUCCESSION.  39 

our  present  observation  goes,  none  of  the  undoubted  Grapto- 
lites  have  ever  been  discovered  in  rocks  later  than  those  known 
upon  other  grounds  to  be  Silurian  ;  but  it  is  possible  that  they 
might  at  any  time  be  detected  in  younger  deposits.  Similarly, 
the  species  and  genera  which  we  now  regard  as  characteristic 
of  the  Lower  Silurian,  may  at  some  future  time  be  found  to 
have  survived  into  the  Upper  Silurian  period.  We  should  not 
forget,  therefore,  in  determining  the  age  of  strata  by  palaeonto- 
logical  evidence,  that  we  are  always  reasoning  upon  generalisa- 
tions which  are  the  result  of  experience  alone,  and  which  are 
liable  to  be  vitiated  by  further  and  additional  discoveries. 

When  the  palaeontological  evidence  as  to  the  age  of  any 
given  set  of  strata  is  corroborated  by  the  physical  evidence,  our 
conclusions  may  be  regarded  as  almost  certain  ;  but  there  are 
certain  limitations  and  fallacies  in  the  palaeontological  method 
of  inquiry  which  deserve  a  passing  mention.  In  the  first 
place,  fossils  are  not  always  present  in  the  stratified  rocks ; 
many  aqueous  rocks  are  unfossiliferous,  through  a  thickness  of 
hundreds  or  even  thousands  of  feet  of  little-altered  sediments ; 
and  even  amongst  beds  which  do  contain  fossils,  we  often  meet 
with  strata  of  many  feet  or  yards  in  thickness  which  are  wholly 
destitute  of  any  traces  of  fossils.  There  are,  therefore,  to 
begin  with,  many  cases  in  which  there  is  no  palaeontological 
evidence  extant  or  available  as  to  the  age  of  a  given  group 
of  strata.  In  the  second  place,  palaeontological  observers  in 
different  parts  of  the  world  are  liable  to  give  different  names 
to  the  same  fossil,  and  in  all  parts  of  the  world  they  are  occa- 
sionally liable  to  group  together  different  fossils  under  the 
same  title.  Both  these  sources  of  fallacy  require  to  be  guarded 
against  in  reasoning  as  to  the  age  of  strata  from  their  fossil 
remains.  Thirdly,  the  mere  fact  of  fossils  being  found  in  beds 
which  are  known  by  physical  evidence  to  be  of  different  ages, 
has  commonly  led  palaeontologists  to  describe  them  as  dif- 
ferent species.  Thus,  the  same  fossil,  occurring  in  successive 
groups  of  strata,  and  with  the  merely  trivial  and  varietal  differ- 
ences due  to  the  gradual  change  in  its  environment,  has  been 
repeatedly  described  as  a  distinct  species,  with  a  distinct 
name,  in  every  bed  in  which  it  was  found.  We  know,  however, 
that  many  fossils  range  vertically  through  many  groups  of  strata, 
and  there  are  some  which  even  pass  through  several  forma- 
tions. The  mere  fact  of  a  difference  of  physical  position 
ought  never  to.be  taken  into  account  at  all  in  considering  and 
determining  the  true  affinities  of  a  fossil.  Fourthly,  the 
results  of  experience,  instead  of  being  an  assistance,  are  some- 
times liable  to  operate  as  a  source  of  error.  When  once, 


40  PRINCIPLES   OF   PALEONTOLOGY. 

namely,  a  generalisation  has  been  established  that  certain 
fossils  occur  in  strata  of  a  certain  age,  palaeontologists  are  apt 
to  infer  that  all  beds  containing  similar  fossils  must  be  of  the 
same  age.  There  is  a  presumption,  of  course,  that  this  infer- 
ence would  be  correct ;  but  it  is  not  a  conclusion  resting  upon 
absolute  necessity,  and  there  might  be  physical  evidence  to 
disprove  it.  Fifthly,  the  physical  geologist  may  lead  the  palae- 
ontologist astray  by  asserting  that  the  physical  evidence  as  to 
the  age  and  position  of  a  given  group  of  beds  is  clear  and  un- 
equivocal, when  such  evidence  may  be,  in  reality,  very  slight 
and  doubtful.  In  this  way,  the  observer  may  be  readily  led 
into  wrong  conclusions  as  to  the  nature  of  the  organic  remains 
— often  obscure  and  fragmentary — which  it  is  his  business  to 
examine,  or  he  may  be  led  erroneously  to  think  that  previous 
generalisations  as  to  the  age  of  certain  kinds  of  fossils  are 
premature  and  incorrect.  Lastly,  there  are  cases  in  which, 
owing  to  the  limited  exposure  of  the  beds,  to  their  being 
merely  of  local  development,  or  to  other  causes,  the  physical 
evidence  as  to  the  age  of  a  given  group  of  strata  may  be  en- 
tirely uncertain  and  unreliable,  and  in  which,  therefore,  the 
observer  has  to  rely  wholly  upon  the  fossils  which  he  may 
meet  with. 

In  spite  of  the  above  limitations  and  fallacies,  there  can  be 
no  doubt  as  to  the  enormous  value  of  palaeontology  in  enab- 
ling us  to  work  out  the  historical  succession  of  the  sedimentary 
rocks.  It  may  even  be  said  that  in  any  case  where  there 
should  appear  to  be  a  clear  and  decisive  discordance  between 
the  physical  and  the  palaeontological  evidence  as  to  the  age 
of  a  given  series  of  beds,  it  is  the  former  that  is  to  be  distrusted 
rather  than  the  latter.  The  records  of  geological  science  con- 
tain not  a  few  cases  in  which  apparently  clear  physical  evi- 
dence of  superposition  has  been  demonstrated  to  have  been 
wrongly  interpreted ;  but  the  evidence  of  palaeontology,  when 
in  any  way  sufficient,  has  rarely  been  upset  by  subsequent 
investigations.  Should  we  find  strata  containing  plants  of  the 
Coal-measures  apparently  resting  upon  other  strata  with  Am- 
monites and  Belemnites,  we  may  be  sure  that  the  physical 
evidence  is  delusive  ;  and  though  the  above  is  an  extreme  case, 
the  presumption  in  all  such  instances  is  rather  that  the  physical 
succession  has  been  misunderstood  or  misconstrued,  than  that 
there  has  been  a  subversion  of  the  recognised  succession  of 
life-forms. 

We  have  seen,  then,  that  as  the  collective  result  of  observa- 
tions made  upon  the  superposition  of  rocks  in  different  locali- 
ties, from  their  mineral  characters,  and  from  their  included 


CHRONOLOGICAL  SUCCESSION.  41 

fossils,  geologists  have  been  able  to  divide  the  entire  stratified 
series  into  a  number  of  different  divisions  or  formations,  each 
characterised  by  a  general  uniformity  of  mineral  composition, 
and  by  a  special  and  peculiar  assemblage  of  organic  forms. 
Each  of  these  primary  groups  is  in  turn  divided  into  a  series  of 
smaller  divisions,  characterised  and  distinguished  in 'the  same 
way.  It  is  not  pretended  for  a  moment  that  all  these  primary 
rock-groups  can  anywhere  be  seen  surmounting  one  another 
regularly.*  There  is  no  region  upon  the  earth  where  all 
the  stratified  formations  can  be  seen  together ;  and,  even 
when  most  of  them  occur  in  the  same  country,  they  can 
nowhere  be  seen  all  succeeding  each  other  in  their  regular  and 
uninterrupted  succession.  The  reason  of  this  is  obvious. 
There  are  many  places — to  take  a  single  example — where  one 
may  see  the  the  Silurian  rocks,  the  Devonian,  and  the  Carbon- 
iferous rocks  succeeding  one  another  regularly,  and  in  their 
proper  order.  This  is  because  the  particular  region  where  this 
occurs  was  always  submerged  beneath  the  sea  while  these  for- 
mations were  being  deposited.  There  are,  however,  many 
more  localities  in  which  one  would  find  the  Carboniferous 
rocks  resting  unconformably  upon  the  Silurians  without  the 
intervention  of  any  strata  which  could  be  referred  to  the 
Devonian  period.  This  might  arise  from  one  of  two  causes : 
i.  The  Silurians  might  have  been  elevated  above  the  sea  im- 
mediately after  their  deposition,  so  as  to  form  dry  land  during 
the  whole  of  the  Devonian  period,  in  which  case,  of  course, 
no  strata  of  the  latter  age  could  possibly  be  deposited  in  that 
area.  2.  The  Devonian  might  have  been  deposited  upon  the 
Silurian,  and  then  the  whole  might  have  been  elevated  above 
the  sea,  and  subjected  to  an  amount  of  denudation  sufficient  to 
remove  the  Devonian  strata  entirely.  In  this  case,  when  the 
land  was  again  submerged,  the  Carboniferous  rocks,  or  any 
younger  formation,  might  be  deposited  directly  upon  Silurian 
strata.  From  one  or  other  of  these  causes,  then,  or  from  subse- 
quent disturbances  and  denudations,  it  happens  that  we  can 

*  As  we  have  every  reason  to  believe  that  dry  land  and  sea  have  existed,  at 
any  rate  from  the  commencement  of  the  Lauremian  period  to  the  present  day, 
it  is  quite  obvious  that  no  one  of  the  great  formations  can  ever,  under  any  cir- 
cumstances, have  extended  over  the  entire  globe.  In  other  words,  no  one  of 
the  formations  can  ever  have  had  a  greater  geographical  extent  than  that  of 
the  seas  of  the  period  in  which  the  formation  was  deposited.  Nor  is  there  any 
reason  for  thinking  that  the  proportion  of  dry  land  to  ocean  has  ever  been 
materially  different  to  what  it  is  at  present,  however  greatly  the  areas  of  sea 
and  land  may  have  changed  as  regards  their  place.  It  follows  from  the  above, 
that  there  is  no  sufficient  basis  for  the  view  that  the  crust  of  the  earth  is  com- 
posed of  a  succession  of  concentric  layers,  like  the  coats  of  an  onion,  each 
layer  representing  one  formation. 


42  PRINCIPLES   OF   PALEONTOLOGY. 

rarely  find  many  of  the  primary  formations  following  one 
another  consecutively  and  in  their  regular  order. 

In  no  case,  however,  do  we  ever  find  the  Devonian  resting 
upon  the  Carboniferous,  or  the  Silurian  rocks  reposing  on  the 
Devonian.  We  have  therefore,  by  a  comparison  of  many 
different  areas,  an  established  order  of  succession  of  the  strati- 
fied formations,  as  shown  in  the  subjoined  ideal  section  of  the 
crust  of  the  earth  (fig.  17). 

The  main  subdivisions  of  the  stratified  rocks  are  known  by 
the  following  names  :  — 

1.  Laurentian. 

2.  Cambrian  (with  Huronian  ?). 

3.  Silurian. 

4.  Devonian  or  Old  Red  Sandstone. 

5.  Carboniferous. 


8.  Jurassic  or  Oolitic. 

9.  Cretaceous. 

10.  Eocene. 

11.  Miocene. 

12.  Pliocene. 

13.  Post-tertiary. 


CHRONOLOGICAL   SUCCESSION. 


43 


IDEAL  SECTION  OF  THE  CRUST  OF  THE  EARTH. 

Fig.  17. 

Post-lertiary  and  Recent. 
Pliocene. 


Cretaceous. 


Oolitic  or  Jurassic. 
U    Triassic. 


iferous. 


Devonian  or  Old  Red  Sandstone. 


Cambrian. 
Huronian. 

Laurentian. 


44  PRINCIPLES   OF   PAL/EON  TO  LOGY. 

Of  these  primary  rock  divisions,  the  Laurentian,  Cambrian, 
Silurian,  Devonian,  Carboniferous,  and  Permian  are  collec- 
tively grouped  together  under  the  name  of  the  Primary  or 
Palceozoic  rocks  (Gr.  palaios,  ancient;  zoe,  life).  Not  only  do 
they  constitute  the  oldest  stratified  accumulations,  but  from 
the  extreme  divergence  between  their  animals  and  plants  and 
those  now  in  existence,  they  may  appropriately  be  considered 
as  belonging  to  an  "Old-Life"  period  of  the  world's  history. 
The  Triassic,  Jurassic,  and  Cretaceous  systems  are  grouped  to- 
gether as  the  Secondary  or  Mesozoic  formations  (Gr.  mesos,  inter- 
mediate ;  zoe,  life) ;  the  organic  remains  of  this  "  Middle-Life  " 
period  being,  on  the  whole,  intermediate  in  their  characters 
between  those  of  the  palaeozoic  epoch  and  those  of  more 
modern  strata.  Lastly,  the  Eocene,  Miocene,  and  Pliocene 
formations  are  grouped  together  as  the  Tertiary  or  Kainozoic 
rocks  (Gr.  kainos,  new ;  zoe,  life) ;  because  they  constitute  a 
"  New-Life"  period,  in  which  the  organic  remains  approximate' 
in  character  to  those  now  existing  upon  the  globe.  The  so- 
called  Post-Tertiary  deposits  are  placed  with  the  Kainozoic,  or 
may  be  considered  as  forming  a  separate  Quaternary  system. 


CHAPTER    IV. 

THE  BREAKS  IN  THE  GEOLOGICAL  AND 
PAL&ONTOLOGICAL  RECORD. 

The  term  "  contemporaneous  "  is  usually  applied  by  geolo- 
gists to  groups  of  strata  in  different  regions  which  contain  the 
same  fossils,  or  an  assemblage  of  fossils  in  which  many  iden- 
tical forms  are  present.  That  is  to  say,  beds  which  contain 
identical,  or  nearly  identical,  fossils,  however  widely  separated 
they  may  be  from  one  another  in  point  of  actual  distance,  are 
ordinarily  believed  to  have  been  deposited  during  the  same 
period  of  the  earth's  history.  This  belief,  indeed,  constitutes 
the  keystone  of  the  entire  system  of  determining  the  age  of 
strata  by  their  fossil  contents;  and  if  we  take  the  word  "con- 
temporaneous" in  a  general  and  strictly  geological  sense,  this 
belief  can  be  accepted  as  proved  beyond  denial.  We  must, 
however,  guard  ourselves  against  too  literal  an  interpretation 
of  the  word  "  contemporaneous,"  and  we  must  bear  in  mind 
the  enormously  -  prolonged  periods  of  time  with  which  the 
geologist  has  to  deal.  When  we  say  that  two  groups  of  strata 


BREAKS  IN  THE  GEOLOGICAL  RECORD.     45 

in  different  regions  are  "  contemporaneous,"  we  simply  mean 
that  they  were  formed  during  the  same  geological  period,  and 
perhaps  at  different  stages  of  that  period,  and  we  do  not  mean  to 
imply  that  they  were  formed  at  precisely  the  same  instant  of  time. 
A  moment's  consideration  will  show  us  that  it  is  only  in  the 
former  sense  that  we  can  properly  speak  of  strata  being  "  con- 
temporaneous ;"  and  that,  in  point  of  fact,  beds  containing 
the  same  fossils,  if  occurring  in  widely  distant  areas,  can  hardly 
be  "  contemporaneous  "  in  any  literal  sense  ;  but  that  the  very 
identity  of  their  fossils  is  proof  that  they  were  deposited  one 
after  the  other.  If  we  find  strata  containing  identical  fossils 
within  the  limits  of  a  single  geographical  region — say  in  Europe 
— then  there  is  a  reasonable  probability  that  these  beds  are 
strictly  contemporaneous,  in  the  sense  that  they  were  deposited 
at  the  same  time.  There  is  a  reasonable  probability  of  this, 
because  there  is  no  improbability  involved  in  the  idea  of  an 
ocean  occupying  the  whole  area  of  Europe,  and  peopled 
throughout  by  many  of  the  same  species  of  marine  animals.  At 
the  present  day,  for  example,  many  identical  species  of  animals 
are  found  living  on  the  western  coasts  of  Britain  and  the 
eastern  coasts  of  North  America,  and  beds  now  in  course  of 
deposition  off  the  shores  of  Ireland  and  the  seaboard  of  the 
state  of  New  York  would  necessarily  contain  many  of  the 
same  fossils.  Such  beds  would  be  both  literally  and  geologi- 
cally contemporaneous;  but  the  case  is  different  if  the  distance 
between  the  areas  where  the  strata  occur  be  greatly  increased. 
We  find,  for  example,  beds  containing  identical  fossils  (the 
Quebec  or  Skiddaw  beds)  in  Sweden,  in  the  north  of  England, 
in  Canada,  and  in  Australia.  Now,  if  all  these  beds  were  con- 
temporaneous, in  the  literal  sense  of  the  term,  we  should  have 
to  suppose  that  the  ocean  at  one  time  extended  uninterrup- 
tedly between  all  these  points,  and  was  peopled  throughout 
the  vast  area  thus  indicated  by  many  of  the  same  animals. 
Nothing,  however,  that  we  see  at  the  present  day  would  justify 
us  in  imagining  an  ocean  of  such  enormous  extent,  and  at  the 
same  time  so  uniform  in  its  depth,  temperature,  and  other 
conditions  of  marine  life,  as  to  allow  the  same  animals  to 
flourish  in  it  from  end  to  end ;  and  the  example  chosen  is 
only  one  of  a  long  and  ever-recurring  series.  It  is  therefore 
much  more  reasonable  to  explain  this,  and  all  similar  cases,  as 
owing  to  the  migration  of  the  fauna,  in  whole  or  in  part,  from 
one  marine  area  to  another.  Thus,  we  may  suppose  an  ocean 
to  cover  what  is  now  the  European  area,  and  to  be  peopled  by 
certain  species  of  animals.  Beds  of  sediment — clay,  sands, 
and  limestones — will  be  deposited  over  the  sea-bottom,  and 


46  PRINCIPLES   OF    PALAEONTOLOGY. 

will  entomb  the  remains  of  the  animals  as  fossils.  After  this 
has  lasted  for  a  certain  length  of  time,  the  European  area  may 
undergo  elevation,  or  may  become  otherwise  unsuitable  for  the 
perpetuation  of  its  fauna ;  the  result  of  which  would  be  that 
some  or  all  of  the  marine  animals  of  the  area  would  migrate  to 
some  more  suitable  region.  Sediments  would  then  be  accumu- 
lated in  the  new  area  to  which  they  had  betaken  themselves, 
and  they  would  then  appear,  for  the  second  time,  as  fossils  in 
a  set  of  beds  widely  separated  from  Europe.  The  second  set 
of  beds  would,  however,  obviously  not  be  strictly  or  literally 
contemporaneous  with  the  first,  but  would  be  separated  from 
them  by  the  period  of  time  required  for  the  migration  of  the 
animals  from  the  one  area  into  the  other.  It  is  only  in  a  wide 
and  comprehensive  sense  that  such  strata  can  be  said  to  be 
contemporaneous. 

It  is  impossible  to  enter  further  into  this  subject  here ;  but 
it  may  be  taken  as  certain  that  beds  in  widely  remote  geogra- 
phical areas  can  only  come  to  contain  the  same  fossils  by 
reason  of  a  migration  having  taken  place  of  the  animals  of 
the  one  area  to  the  other.  That  such  migrations  can  and  do 
take  place  is  quite  certain,  and  this  is  a  much  more  reasonable 
explanation  of  the  observed  facts  than  the  hypothesis  that  in 
former  periods  the  conditions  of  life  were  much  more  uniform 
than  they  are  at  present,  and  that,  consequently,  the  same 
organisms  were  able  to  range  over  the  entire  globe  at  the  same 
time.  It  need  only  be  added,  that  taking  the  evidence  of  the 
present  as  explaining  the  phenomena  of  the  past — the  only 
safe  method  of  reasoning  in  geological  matters — we  have 
abundant  proof  that  deposits  which  are  actually  contempo- 
raneous, in  the  strict  sense  of  the  term,  do  not  contain  the  same, 
fossils,  if  far  removed  from  one  another  in  point  of  distance. 
Thus,  deposits  of  various  kinds  are  now  in  process  of  forma- 
tion in  our  existing  seas,  as,  for  example,  in  the  Arctic  Ocean, 
the  Atlantic,  and  the  Pacific,  and  many  of  these  deposits  are 
known  to  us  by  actual  examination  and  observation  with  the 
sounding-lead  and  dredge.  But  it  is  hardly  necessary  to  add 
that  the  animal  remains  contained  in  these  deposits — the 
fossils  of  some  future  period — instead  of  being  identical,  are 
widely  different  from  one  another  in  their  characters. 

We  have  seen,  then,  that  the  entire  stratified  series  is  capable 
of  subdivision  into  a  number  of  definite  rock-groups  or  "forma- 
tions," each  possessing  a  peculiar  and  characteristic  assem- 
blage of  fossils,  representing  the  "life"  of  the  "period"  in 
which  the  formation  was  deposited.  We  have  still  to  inquire 
shortly  how  it  came  to  pass  that  two  successive  formations 


BREAKS  IN  THE  GEOLOGICAL  RECORD.      47 

should  thus  be  broadly  distinguished  by  their  life-forms,  and 
why  they  should  not  rather  possess  at  any  rate  a  majority  of 
identical  fossils.  It  was  originally  supposed  that  this  could  be 
explained  by  the  hypothesis  that  the  close  of  each  formation 
was  accompanied  by  a  general  destruction  of  all  the  living 
beings  of  the  period,  and  that  the  commencement  of  each 
new  formation  was  signalised  by  the  creation  of  a  number  of 
brand-new  organisms,  destined  to  figure  as  the  characteristic 
fossils  of  the  same.  This  theory,  however,  ignores  the  fact 
that  each  formation — as  to  which  we  have  any  sufficient 
evidence — contains  a  few,  at  least,  of  the  life-forms  which 
existed  in  the  preceding  period;  and  it  invokes  forces  and 
processes  of  which  we  know  nothing,  and  for  the  supposed 
action  of  which  we  cannot  account.  The  problem  is  an  un- 
deniably difficult  one,  and  it  will  not  be  possible  here  to  give 
more  than  a  mere  outline  of  the  modern  views  upon  the  sub- 
ject. Without  entering  into  the  at  present  inscrutable  question 
as  to  the  manner  in  which  new  life-forms  are  introduced  upon 
the  earth,  it  may  be  stated  that  almost  all  modern  geologists 
hold  that  the  living  beings  of  any  given  formation  are  in  the 
main  modified  forms  of  others  which  have  preceded  them.  It 
is  not  believed  that  any  general  or  universal  destruction  of 
life  took  place  at  the  termination  of  each  geological  period,  or 
that  a  general  introduction  of  new  forms  took  place  at  the 
commencement  of  a  new  period.  It  is,  on  the  contrary, 
believed  that  the  animals  and  plants  of  any  given  period  are 
for  the  most  part  (or  exclusively)  the  lineal  but  modified 
descendants  of  the  animals  and  plants  of  the  immediately  pre- 
ceding period,  and  that  some  of  them,  at  any  rate,  are  con- 
tinued into  the  next  succeeding  period,  either  unchanged,  or 
so  far  altered  as  to  appear  as  new  species.  To  discuss  these 
views  in  detail  would  lead  us  altogether  too  far.  but  there  is 
one  very  obvious  consideration  which  may  advantageously 
receive  some  attention.  It  is  obvious,  namely,  that  the  great 
discordance  which  is  found  to  subsist  between  the  animal 
life  of  any  given  formation  and  that  of  the  next  succeeding 
formation,  and  which  no  one  denies,  would  be  a  fatal  blow  to 
the  views  just  alluded  to,  unless  admitting  of  some  satisfactory 
explanation.  Nor  is  this  discordance  one  purely  of  life-forms, 
for  there  is  often  a  physical  break  in  the  successions  of  strata 
as  well.  Let  us  therefore  briefly  consider  how  far  these 
interruptions  and  breaks  in  the  geological  and  palseonto- 
logical  record  can  be  accounted  for,  and  still  allow  us  to 
believe  in  some  theory  of  continuity  as  opposed  to  the  doc- 
trine of  intermittent  and  occasional  action. 


48  PRINCIPLES   OF   PALAEONTOLOGY. 

In  the  first  place,  it  is  perfectly  clear  that  if  we  admit  the 
conception  above  mentioned  of  a  continuity  of  life  from  the 
Laurentian  period  to  the  present  day,  we  could  never  prove 
our  view  to  be  correct,  unless  we  could  produce  in  evidence 
fossil   examples   of  all  the   kinds  of  animals  and  plants  that 
have  lived  and  died  during  that  period.     In  order  to  do  this, 
we  should  require,  to  begin  with,  to  have  access  to  an  abso- 
lutely  unbroken   and   perfect  succession  of  all  the  deposits 
which   have   ever  been  laid  down  since  the  beginning.     If, 
however,  we  ask  the  physical  geologist  if  'he  is  in  possession 
of  any  such  uninterrupted  series,  he  will  at  once  answer  in  the 
negative.    So  far  from  the  geological  series  being  a  perfect  one, 
it  is  interrupted  by  numerous  gaps  of  unknown  length,  many 
of  which  we  can  never  expect  to  fill  up.     Nor  are  the  proofs 
of  this  far  to  seek.     Apart  from  the  facts  that  we  have  hitherto 
examined  only  a  limited  portion  of  the  dry  land,  that  nearly 
two-thirds  of  the  entire  area  of  the  globe  is  inaccessible  to 
geological  investigation  in  consequence  of  its  being  covered 
by  the  sea,  that  many  deposits  can  be  shown  to  have  been 
more  or  less  completely  destroyed  subsequent  to  their  depo- 
sition, and  that  there  may  be  many  areas  in  which  living  beings 
exist  where  no  rock  is  in  process  of  formation,  we  have  the  broad 
fact  that  rock-deposition  only  goes  on  to  any  extent  in  water, 
and  that  the  earth  must  have  always  consisted  partly  of  dry 
land  and  partly  of  water — at  any  rate,  so  far  as  any  period  of 
which  we  have  geological  knowledge  is  concerned.     There 
must,  therefore,  always  have  existed,  at  some  part  or  another 
of  the  earth's  surface,  areas  where  no  deposition  of  rock  was 
going  on,  and  the  proof  of  this  is  to  be  found  in  the  well- 
known  phenomenon  of  "unconformabUity?  Whenever,  namelv, 
deposition  of  sediment  is  continuously  going  on  within   the 
limits  of  a  single  ocean,  the  beds  which  are  laid  down  succeed 
one  another  in  uninterrupted  and  regular  sequence.      Such 
beds  are  said  to  be  "  conformable,"  and  there  are  many  rock- 
groups  known  where  one  may  pass  through  fifteen  or  twenty 
thousand  feet  of  strata  without  a  break — indicating  that  the 
beds  had  been  deposited  in  an  area  which  remained  continu- 
ously covered  by  the  sea.     On  the  other  hand,  we  commonly 
find  that  there  is  no  such  regular  succession  when  we  pass 
from  one  great  formation  to  another,  but  that,  on  the  contrary, 
the  younger  formation  rests  "  un  con  form  ably,"  as  it  is  called, 
either  upon  the  formation  immediately  preceding  it  in  point  of 
time,  or  upon  some  still  older  one.     The  essential  physical 
feature  of  this  unconformability  is  that  the  beds  of  the  younger 
formation  rest  upon  a  worn  and  eroded  surface  formed  by  the 


BREAKS  IN  THE  GEOLOGICAL  RECORD. 


49 


beds  of  the  older  series  (fig.  18);  and  a  moment's  considera- 
tion will  show  us  what  this  indicates.     It  indicates,  beyond 


Fig.  18.— Section  showing  strata  of  Tertiary  age  (<r)  resting  upon  a  worn  and  eroded 
surface  of  White  Chalk  (b),  the  stratification  of  which  is  marked  by  lines  of  flint. 

the  possibility  of  misconception,  that  there  was  an  interval 
between  the  deposition  of  the  older  series  and  that  of  the 
newer  series  of  strata ;  and  that  during  this  interval  the  older 
beds  were  raised  above  the  sea-level,  so  as  to  form  dry  land, 
and  were  subsequently  depressed  again  beneath  the  waters,  to 
receive  upon  their  worn  and  wasted  upper  surface  the  sedi- 
ments of  the  later  group.  During  the  interval  thus  indicated, 
the  deposition  of  rock  must  of  necessity  have  been  proceeding 
more  or  less  actively  in  other  areas.  Every  unconformity, 
therefore,  indicates  that  at  the  spot  where  it  occurs,  a  more  or 
less  extensive  series  of  beds  must  be  actually  missing ;  and 
though  we  may  sometimes  be  able  to  point  to  these  missing 
strata  in  other  areas,  there  yet  remains  a  number  of  unconfor- 
mities for  which  we  cannot  at  present  supply  the  deficiency 
even  in  a  partial  manner. 

It  follows  from  the  above  that  the  series  of  stratified  deposits 
is  to  a  greater  or  less  extent  irremediably  imperfect ;  and  in 
this  imperfection  we  have  one  great  cause  why  we  can  never 
obtain  a  perfect  series  of  all  the  animals  and  plants  that  have 
lived  upon  the  globe.  Wherever  one  of  these  great  physical 
gaps  occurs,  we  find,  as  we  might  expect,  a  corresponding 
break  in  the  series  of  life-forms.  In  other  words,  whenever  we 
find  two  formations  to  be  unconformable,  we  shall  always  find 
at  the  same  time  that  there  is  a  great  difference  in  their  fossils, 
and  that  many  of  the  fossils  of  the  older  formation  do  not  sur- 
vive into  the  newer,  whilst  many  of  those  in  the  newer  are  not 
known  to  occur  in  the  older.  The  cause  of  this  is,  obviously, 


5O  PRINCIPLES   OF   PALAEONTOLOGY. 

that  the  lapse  of  time,  indicated  Ly  the  unconformability,  has 
been  sufficiently  great  to  allow  of  the  dying  out  or  modifica- 
tion of  rainy  of  the  older  forms  of  life,  and  the  introduction  of 
new  ones  by  immigration. 

Apart,  however,  altogether,  from  these  great  physical  breaks 
and  their  corresponding  breaks  in  life,  there  are  other  reasons 
why  we  can  never  become  more  than  partially  acquainted  with 
the  former  denizens  of  the  globe.  Foremost  amongst  these  is 
the  fact  that  an  enormous  number  of  animals  possess  no  hard 
parts  of  the  nature  of  a  skeleton,  and  are  therefore  incapable, 
under  any  ordinary  circumstances,  of  leaving  behind  them  any 
traces  of  their  existence.  It  is  true  that  there  are  caser>  in 
which  animals  in  themselves  completely  soft-bodied  are  never- 
theless able  to  leave  marks  by  which  their  former  presence  can 
be  detected.  Thus  every  geologist  is  familiar  with  the  wind- 
ing and  twisting  "  trails  "  formed  on  the  surface  of  the  strata 
by  sea -worms;  and  the  impressions  left  by  the  stranded 
carcases  of  Jelly-fishes  on  the  fine-grained  lithographic  slates 
of  Solenhofen  supply  us  with  an  example  of  how  a  creature 
which  is  little  more  than  "organised  sea -water"  may  still 
make  an  abiding  mark  upon  the  sands  of  time.  As  a  general 
rule,  however,  animals  which  have  no  skeletons  are  incapable 
of  being  preserved  as  fossils,  and  hence  there  must  always 
have  been  a  vast  number  of  different  kinds  of  marine  animals 
of  which  we  have  absolutely  no  record  whatever.  Again, 
almost  all  the  fossiliferous  rocks  have  been  laid  down  in  water; 
and  it  is  a  necessary  result  of  this  that  the  great  majority  of 
fossils  are  the  remains  of  aquatic  animals.  The  remains  of 
air-breathing  animals,  whether  of  the  inhabitants  of  the  land 
or  of  the  air  itself,  are  comparatively  rare  as  fossils,  and  the 
record  of  the  past  existence  of  these  is  much  more  imperfect 
than  is  the  case  with  animals  living  in  water.  Moreover,  the 
fossiliferous  deposits  are  not  only  almost  exclusively  aqueous 
formations,  but  the  great  'majority  are  marine,  and  only  a  com- 
paratively small  number  have  been  formed  by  lakes  and  rivers. 
It  follows  from  the  foregoing  that  the  pal  aeon  tological  record 
is  fullest  and  most  complete  so  far  as  sea-animals  are  concerned, 
though  even  here  we  find  enormous  gaps,  owing  to  the  absence 
of  hard  structures  in  many  great  groups  ;  of  animals  inhabiting 
fresh  waters  our  knowledge  is  rendered  still  further  incomplete 
by  the  small  proportion  that  fluviatile  and  lacustrine  deposits 
bear  to  marine ;  whilst  we  have  only  a  fragmentary  acquaint- 
ance with  the  air-breathing  animals  which  inhabited  the  earth 
during  past  ages. 

Lastly,  the  imperfection  of  the  palasontological  record,  due 


BREAKS  IN  THE  GEOLOGICAL  RECORD.      51 

to  the  causes  above  enumerated,  is  greatly  aggravated,  especi- 
ally as  regards  the  earlier  portion  of  the  earth's  history,  by  the 
fact  that  many  rocks  which  contained  fossils  when  deposited 
have  since  been  rendered  barren  of  organic  remains.  The 
principal  cause  of  this  common  phenomenon  is  what  is  known 
as  "  metamorphism  " — that  is,  the  subjection  of  the  rock  to  a 
sufficient  amount  of  heat  to  cause  a  rearrangement  of  its  par- 
ticles. When  at  all  of  a  pronounced  character,  the  result  of 
metamorphic  action  is  invariably  the  obliteration  of  any  fossils 
which  might  have  been  originally  present  in  the  rock.  Meta- 
morphism may  affect  rocks  of  any  age,  though  naturally  more 
prevalent  in  the  older  rocks,  and  to  this  cause  must  be  set 
down  an  irreparable  loss  of  much  fossil  evidence.  The  most 
striking  example  which  is  to  be  found  of  this  is  the  great  Lau- 
rentian  series,  which  comprises  some  30,000  feet  of  highly- 
metamorphosed  sediments,  but  which,  with  one  not  wholly 
undisputed  exception,  has  as  yet  yielded  no  remains  of  living 
beings,  though  there  is  strong  evidence  of  the  former  existence 
in  it  of  fossils. 

Upon  the  whole,  then,  we  cannot  doubt  that  the  earth's 
crust,  so  far  as  yet  deciphered  by  us,  presents  us  with  but  a 
very  imperfect  record  of  the  past.  Whether  the  known  and 
admitted  imperfections  of  the  geological  and  palaeontological 
records  are  sufficiently  serious  to  account  satisfactorily  for  the 
deficiency  of  direct  evidence  recognisable  in  some  modern 
hypotheses,  may  be  a  matter  of  individual  opinion.  There 
can,  however,  be  little  doubt  that  they  are  sufficiently  extensive 
to  throw  the  balance  of  evidence  decisively  in  favour  of  some 
theory  of  continuity,  as  opposed  to  any  theory  of  intermittent 
and  occasional  action.  The  apparent  breaks  which  divide  the 
great  series  of  the  stratified  rocks  into  a  number  of  isolated 
formations,  are  not  marks  of  mighty  and  general  convulsions 
of  nature,  but  are  simply  indications  of  the  imperfection  of 
our  knowledge.  Never,  in  all  probability,  shall  we  be  able  to 
point  to  a  complete  series  of  deposits,  or  a  complete  succession 
of  life  linking  one  great  geological  period  to  another.  Never- 
theless, we  may  well  feel  sure  that  such  deposits  and  such  an 
unbroken  succession  must  have  existed  at  one  time.  We  are 
compelled  to  believe  that  nowhere  in  the  long  series  of  the 
fossiliferous  rocks  has  there  been  a  total  break,  but  that  there 
must  have  been  a  complete  continuity  of  life,  and  a  more  or 
less  complete  continuity  of  sedimentation,  from  the  Laurentian 
period  to  the  present  day.  One  generation  hands  on  the 
lamp  of  life  to  the  next,  and  each  system  of  rocks  is  the  direct 
offspring  of  those  which  preceded  it  in  time.  Though  there 


52  PRINCIPLES   OF   PALAEONTOLOGY. 

has  not  been  continuity  in  any  given  area,  still  the  geological 
chain  could  never  have  been  snapped  at  one  point,  and  taken 
up  again  at  a  totally  different  one.  Thus  we  arrive  at  the 
conviction  that  continuity  is  the  fundamental  law  of  geology, 
as  it  is  of  the  other  sciences,  and  that  the  lines  of  demarca- 
tion between  the  great  formations  are  but  gaps  in  our  own 
knowledge. 


CHAPTER    V. 

CONCLUSIONS  TO  BE  DRAWN  FROM  FOSSILS. 

We  have  already  seen  that  geologists  have  been  led  by  the 
study  of  fossils  to  the  all-important  generalisation  that  the  vast 
series  of  the  Fossiliferous  or  Sedimentary  Rocks  may  be 
divided  into  a  number  of  definite  groups  or  "  formations," 
each  of  which  is  characterised  by  its  organic  remains.  It  may 
simply  be  repeated  here  that  these  formations  are  not  properly 
and  strictly  characterised  by  the  occurrence  in  them  of  any 
one  particular  fossil.  It  may  be  that  a  formation  contains 
some  particular  fossil  or  fossils  not  occurring  out  of  that 
formation,  and  that  in  this  way  an  observer  may  identify  a 
given  group  with  tolerable  certainty.  It  very  often  happens, 
indeed,  that  some  particular  stratum,  or  sub-group  of  a  series, 
contains  peculiar  fossils,  by  which  its  existence  may  be  deter- 
mined in  various  localities.  As  before  remarked,  however,  the 
great  formations  are  characterised  properly  by  the  association 
of  certain  fossils,  by  the  predominance  of  certain  families  or 
orders,  or  by  an  assemblage  of  fossil  remains  representing  the 
"  life  "  of  the  period  in  which  the  formation  was  deposited. 

Fossils,  then,  enable  us  to  determine  the  age  of  the  deposits 
in  which  they  occur.  Fossils  further  enable  us  to  come  to 
very  important  conclusions  as  to  the  mode  in  which  the  fossil- 
iferous  bed  was  deposited,  and  thus  as  to  the  condition  of  the 
particular  district  or  region  occupied  by  the  fossiliferous  bed 
at  the  time  of  the  formation  of  the  latter.  If,  in  the  first 
place,  the  bed  contain  the  remains  of  animals  such  as  now 
inhabit  rivers,  we  know  that  it  is  "  fluviatile"  in  its  origin,  and 
that  it  must  at  one  time  have  either  formed  an  actual  river- 
bed, or  been  deposited  by  the  overflowing  of  an  ancient 
stream.  Secondly,  if  the  bed  contain  the  remains  of  shell- 
fish, minute  crustaceans,  or  fish,  such  as  now  inhabit  lakes, 


CONCLUSIONS   TO   BE   DRAWN   FROM   FOSSILS.       53 

we  know  that  it  is  "  lacustrine,"  and  was  deposited  beneath 
the  waters  of  a  former  lake.  Thirdly,  if  the  bed  contain  the 
remains  of  animals  such  as  now  people  the  ocean,  we  know 
that  it  is  "  marine  "  in  its  origin,  and  that  it  is  a  fragment  of 
an  old  sea-bottom. 

We  can,  however,  often  determine  the  conditions  under 
which  a  bed  was  deposited  with  greater  accuracy  than  this. 
If,  for  example,  the  fossils  are  of  kinds  resembling  the  marine 
animals  now  inhabiting  shallow  waters,  if  they  are  accompanied 
by  the  detached  relics  of  terrestrial  organisms,  or  if  they  are 
partially  rolled  and  broken,  we  may  conclude  that  the  lossil- 
iferous  deposit  was  laid  down  in  a  shallow  sea,  in  the  immediate 
vicinity  of  a  coast-line,  or  as  an  actual  shore-deposit.  If,  again, 
the  remains  are  those  of  animals  such  as  now  live  in  the  deeper 
parts  of  the  ocean,  and  there  is  a  very  sparing  intermixture  of 
extraneous  fossils  (such  as  the  bones  of  birds  or  quadrupeds, 
or  the  remains  of  plants),  we  may  presume  that  the  deposit  is 
one  of  deep  water.  In  other  cases,  we  may  find,  scattered 
through  the  rock,  and  still  in  their  natural  position,  the  valves 
of  shells  such  as  we  know  at  the  present  day  as  living  buried 
in  the  sand  or  mud  of  the  sea- shore  or  of  estuaries.  In  other 
cases,  the  bed  may  obviously  have  been  an  ancient  coral-reef, 
or  an  accumulation  of  social  shells,  like  Oysters.  Lastly,  if  we 
find  the  deposit  to  contain  the  remains  of  marine  shells,  but 
that  these  are  dwarfed  of  their  fair  proportions  and  distorted 
in  figure,  we  may  conclude  that  it  was  laid  down  in  a  brackish 
sea,  such  as  the  Baltic,  in  which  the  proper  saltness  was  want- 
ing, owing  to  its  receiving  an  excessive  supply  of  fresh  water. 

In  the  preceding,  we  have  been  dealing  simply  with  the 
remains  of  aquatic  animals,  and  we  have  seen  that  certain  con- 
clusions can  be  accurately  reached  by  an  examination  of  these. 
As  regards  the  determination  of  the  conditions  of  deposition 
from  the  remains  of  aerial  and  terrestrial  animals,  or  from 
plants,  there  is  not  such  an  absolute  certainty.  The  remains 
of  land-animals  would,  of  course,  occur  in  "  sub-aerial  "  deposits 
—  that  is,  in  beds,  like  blown  sand,  accumulated  upon  the  land. 
Most  of  the  remains  of  land-animals,  Tiowever,  are  found  in 
deposits  which  have  been  laid  down  in  water,  and  they  owe 
their  present  position  to  the  fact  that  their  former  owners  were 
drowned  in  rivers  or  lakes,  or  carried  out  to  sea  by  streams. 
Birds,  Flying  Reptiles,  and  Flying  Mammals  might  also  simi- 
larly find  their  way  into  aqueous  deposits ;  but  it  is  to  be  re- 
membered that  many  birds  and  mammals  habitually  spend  a 
great  part  of  their  time  in  the  water,  and  that  these  might  there- 
fore be  naturally  expected  to  present  themselves  as  fossils  in 


54 


PRINCIPLES 


PALEONTOLOGY. 


Sedimentary  Rocks.  Plants,  again,  even  when  undoubtedly 
such  as  must  have  grown  on  land,  do  not  prove  that  the  bed 
in  which  they  occur  was  formed  on  land.  Many  of  the  remains 
of  plants  known  to  us  are  extraneous  to  the  bed  in  which  they 
are  now  found,  having  reached  their  present  site  by  falling  into 
Likes  or  rivers,  or  being  carried  out  to  sea  by  floods  or  gales  of 
wind.  There  are,  however,  many  cases  in  which  plants  have 
undoubtedly  grown  on  the  very  spot  where  we  now  find  them. 
Thus  it  is  now  generally  admitted  that  the  great  coal-fields 
of  the  Carboniferous  age  are  the  result  of  the  growth  in  situ 
of  the  plants  which  compose  coal,  and  that  these  grew 

on  vast  marshy  or  partially 
submerged  tracts  of  level 
alluvial  land.  We  have, 
however,  distinct  evidence 
of  old  land-surfaces,  both  in 
the  Coal-measures  and  in 
other  cases  (as,  for  instance, 
in  the  well-known  "dirt- 
bed  "  of  the  Purbeck  series). 
When,  for  example,  we  find 
the  erect  stumps  of  trees 
standing  at  right  angles 
to  the  surrounding  strata, 
we  know  that  the  surface 
through  which  these  send 
their  roots  was  at  one  time 
the  surface  of  the  dry  land, 
or,  in  other  words,  was  an 
ancient  soil  (fig.  19). 

In  many  cases  fossils  en- 
able us  to  come  to  important 
conclusions  as  to  the  climate 
of  the  period  in  which  they 
lived,  but  only  a  few  in- 
stances of  this  can  be  here 
adduced.  As  fossils  in  the  majority  of  instances  are  the  re- 
mains of  marine  animals,  it  is  mostly  the  temperature  of  the 
sea  which  can  alone  be  determined  in  this  way;  and  it  is  import- 
ant to  remember  that,  owing  to  the  existence  of  heated  currents, 
the  marine  climate  of  a  given  area  does  not  necessarily  imply  a 
correspondingly  warm  climate  in  the  neighbouring  land.  Land- 
climates  can  only  be  determined  by  the  remains  of  land-ani- 
mals or  land-plants,  and  these  are  comparatively  rare  as  fossils. 
It  is  also  important  to  remember  that  all  conclusions  on  this 


Fig.  19.— Erect  Tree  containing  Reptilian 
remains.  Coal-measures,  Nova  Scotia.  (After 
Dawsoa.) 


CONCLUSIONS   TO   BE    DRAWN   FROM   FOSSILS.       55 

head  are  really  based  upon  the  present  distribution  of  animal 
and  vegetable  life  on  the  globe,  and  are  therefore  liable  to  be 
vitiated  by  the  following  considerations  : — 

a.  Most  fossils  are  extinct,  and  it  is  not  certain  that  the 
habits  and  requirements  of  any  extinct  animal  were    exactly 
similar  to  those  of  its  nearest  living  relative. 

b.  When  we  get  very  far  back  in  time,  we  meet  with  groups 
of  organisms  so  unlike  anything  we  know  at  the  present  day  as 
to  render  all  conjectures  as  to  climate  founded  upon  their  sup- 
posed habits  more  or  less  uncertain  and  unsafe. 

c.  In  the  case  of  marine  animals,  we  are  as  yet  very  far  from 
knowing  the  exact  limits  of  distribution  of  many  species  within 
our  present  seas  ;  so  that  conclusions  drawn  from  living  forms 
as  to  extinct  species  are  apt  to  prove  incorrect.     For  instance, 
it  has  recently  been  shown  that  many  shells  formerly  believed 
to  be  confined  to  the  Arctic  Seas  have,  by  reason  of  the  ex- 
tension of  Polar  currents,  a  wide  range  to  the  south  ;  and  this 
has  thrown   doubt   upon   the   conclusions  drawn  from  fossil 
shells  as  to  the  Arctic  conditions  under  which  certain  beds 
were  supposed  to  have  been  deposited. 

d.  The  distribution  of  animals  at  the  present  day  is  certainly 
dependent  upon  other  conditions  beside  climate  alone ;  and 
the  causes  which  now  limit  the  range  of  given  animals  are 
certainly  such  as  belong  to  the  existing  order  of  things.     But 
the  establishment  of  the  present  order  of  things  does  not  date 
back  in  many  cases  to  the  introduction  of  the  present  species 
of  animals.     Even  in  the  case,  therefore,  of  existing  species  of 
animals,  it  can  often  be  shown  that  the  past  distribution  of  the 
species  was  different  formerly  to  what  it  is  now,  not  necessarily 
because  the  climate  has  changed,  but  because  of  the  alteration 
of  other  conditions  essential  to  the  life  of  the  species  or  con- 
ducing to  its  extension. 

Still,  we  are  in  many  cases  able  to  draw  completely  reliable 
conclusions  as  to  the  climate  of  a  given  geological  period,  by 
an  examination  of  the  fossils  belonging  to  that  period.  Among 
the  more  striking  examples  of  how  the  past  climate  of  a  region 
may  be  deduced  from  the  study  of  the  organic  remains  con- 
tained in  its  rocks,  the  following  may  be  mentioned  :  It  has 
been  shown  that  in  Eocene  times,  or  at  the  commencement 
of  the  Tertiary  period,  the  climate  of  what  is  now  Western 
Europe  was  of  a  tropical  or  sub-tropical  character.  Thus  the 
Eocene  beds  are  found  to  contain  the  remains  of  shells  such 
as  now  inhabit  tropical  seas,  as,  for  example,  Cowries  and 
Volutes  ;  and  with  these  are  the  fruits  of  palms,  and  the 
remains  of  other  tropical  plants.  It  has  been  shown,  again, 


56  PRINCIPLES   OF    PALEONTOLOGY. 

that  in  Miocene  times,  or  about  the  middle  of  the  Tertiary 
period,  Central  Europe  was  peopled  with  a  luxuriant  flora 
resembling  that  of  the  warmer  parts  of  the  United  States,  and 
leading  to  the  conclusion  that  the  mean  annual  temperature 
must  have  been  at  least  30°  hotter  than  it  is  at  present.  It 
has  been  shown  that,  at  the  same  time,  Greenland,  now  buried 
beneath  a  vast  ice-shroud,  was  warm  enough  to  support  a  large 
number  of  trees,  shrubs,  and  other  plants,  such  as  inhabit  the 
temperate  regions  of  the  globe.  Lastly,  it  has  been  shown, 
upon  physical  as  well  as  pal3eontological  evidence,  that  the 
greater  part  of  the  North  Temperate  Zone,  at  a  comparatively 
recent  geological  period,  has  been  visited  with  all  the  rigours 
of  an  Arctic  climate,  resembling  that  of  Greenland  at  the  pre- 
sent day.  This  is  indicated  by  the  occurrence  of  Arctic  shells 
in  the  superficial  deposits  of  this  period,  whilst  the  Musk-ox 
and  the  Reindeer  roamed  far  south  of  their  present  limits. 

Lastly,  it  was  from  the  study  of  fossils  that  geologists  learnt 
originally  to  comprehend  a  fact  which  may  be  regarded  as  of 
cardinal  importance  in  all  modern  geological  theories  and 
speculations — namely,  that  the  crust  of  the  earth  is  liable  to 
local  elevations  and  subsidences.  For  long  after  the  remains 
of  shells  and  other  marine  animals  were  for  the  first  time  ob- 
served in  the  solid  rocks  forming  the  dry  land,  and  at  great 
heights  above  the  sea-level,  attempts  were  made  to  explain  this 
almost  unintelligible  phenomenon  upon  the  hypothesis  that 
the  fossils  in  question  were  not  really  the  objects  they  repre- 
sented, but  were  in  truth  mere  lusus  natures,  due  to  some 
"plastic  virtue  la'ent  in  the  earth."  The  common-sense  of 
scientific  men,  however,  soon  rejected  this  idea,  and  it  was 
agreed  by  universal  consent  that  these  bodies  really  were  the 
remains  of  animals  which  formerly  lived  in  the  sea.  When 
once  this  was  admitted,  the  further  steps  were  comparatively 
easy,  and  at  the  present  day  no  geological  doctrine  stands  on 
a  firmer  basis  than  that  which  teaches  us  that  our  present  con- 
tinents and  islands,  fixed  and  immovable  as  they  appear,  have 
been  repeatedly  sunk  beneath  the  ocean. 


THE   BIOLOGICAL    RELATIONS   OF   FOSSILS.          5/ 

CHAPTER   VI. 
THE  BIOLOGICAL  RELATIONS  OF  FOSSILS. 

Not  only  have  fossils,  as  \ve  have  seen,  a  most  important 
bearing  upon  the  sciences  of  Geology  and  Physical  Geography, 
but  they  have  relations  of  the  most  complicated  and  weighty 
character  with  the  numerous  problems  connected  with  the 
study  of  living  beings,  or  in  other  words,  with  the  science  of 
Biology.  To  such  an  extent  is  this  the  case,  that  no  adequate 
comprehension  of  Zoology  and  Botany,  in  their  modern 
form,  is  so  much  as  possible  without  some  acquaintance  with 
the  types  of  animals  and  plants  which  have  passed  away. 
There  are  also  numerous  speculative  questions  in  the  domain 
of  vital  science,  which,  if  soluble  at  all,  can  only  hope  to  find 
their  key  in  researches  carried  out  on  extinct  organisms.  To 
discuss  fully  the  biological  relations  of  fossils  would,  there- 
fore, afford  matter  for  a  separate  treatise ;  and  all  that  can  be 
done  here  is  to  indicate  very  cursorily  the  principal  points  to 
which  the  attention  of  the  palseontological  student  ought  to 
be  directed. 

In  the  first  place,  the  great  majority  of  fossil  animals  and 
plants  are  "  extinct " — that  is  to  say,  they  belong  to  species 
which  are  no  longer  in  existence  at  the  present  day.  So  far, 
however,  from  there  being  any  truth  in  the  old  view  that  there 
were  periodic  destructions  of  all  the  living  beings  in  existence 
upon  the  earth,  followed  by  a  corresponding  number  of  new 
creations  of  animals  and  plants,  the  actual  facts  of  the  case  show 
that  the  extinction  of  old  forms  and  the  introduction  of  new 
forms  have  been  processes  constantly  going  on  throughout  the 
whole  of  geological  time.  Every  species  seems  to  come  into 
being  at  a  certain  definite  point  of  time,  and  to  finally  dis- 
appear at  another  definite  point ;  though  there  are  few  in- 
stances indeed,  if  there  are  any,  in  which  our  present  know- 
ledge would  permit  us  safely  to  fix  with  precision  the  times  of 
entrance  and  exit.  There  are,  moreover,  marked  differences 
in  the  actual  time  during  which  different  species  remained  in 
existence,  and  therefore  corresponding  differences  in  their 
"vertical  range,"  or,  in  other  words,  in  the  actual  amount  and 
thickness  of  strata  through  which  they  present  themselves  as 
fossils.  Some  species  are  found  to  range  through  two  or  even 
three  formations,  and  a  few  have  an  even  more  extended  life. 
More  commonly  the  species  which  begin  in  the  commence- 


58  PRINCIPLES   OF    PALEONTOLOGY. 

ment  of  a  great  formation  die  out  at  or  before  its  close,  whilst 
those  which  are  introduced  for  the  first  time  near  the  middle 
or  end  of  the  formation  may  either  become  extinct,  or  may 
pass  on  into  the  next  succeeding  formation.  As  a  general 
rule,  it  is  the  animals  which  have  the  lowest  and  simplest 
organisation  that  have  the  longest  range  in  time,  and  the 
additional  possession  of  microscopic  or  minute  dimensions 
seems  also  to  favour  longevity.  Thus  some  of  the  Forami- 
nifera  appear  to  have  survived,  with  little  or  no  perceptible 
alteration,  from  the  Silurian  period  to  the  present  day  ;  whereas 
large  and  highly-organised  animals,  though  long-lived  as  indi- 
viduals, rarely  seem  to  live  long  specifically,  and  have,  there- 
fore, usually  a  restricted  vertical  range.  Exceptions  to  this, 
however,  are  occasionally  to  be  found  in  some  "persistent 
types,"  which  extend  through  a  succession  of  geological 
periods  with  very  little  modification.  Thus  the  existing 
Lampshells  of  the  genus  Lingula  are  little  changed  from  the 
Lingulce  which  swarmed  in  the  Lower  Silurian  seas ;  and  the 
existing  Pearly  Nautilus  is  the  last  descendant  of  a  clan 
nearly  as  ancient.  On  the  other  hand,  some  forms  are  singu- 
larly restricted  in  their  limits,  and  seem  to  have  enjoyed  a 
comparatively  brief  lease  of  life.  An  example  of  this  is  to 
be  found  in  many  of  the  Ammonites — close  allies  of  the  Nau- 
tilus— which  are  often  confined  strictly  to  certain  zones  of 
strata,  in  some  cases  of  very  insignificant  thickness. 

Of  the  causes  of  extinction  amongst  fossil  animals  and 
plants,  we  know  little  or  nothing.  All  we  can  say  is,  that  the 
attributes  which  constitute  a  species  do  not  seem  to  be  intrin- 
sically endowed  with  permanence,  any  more  than  the  attri- 
butes which  constitute  an  individual,  though  the  former  may 
endure  whilst  many  successive  generations  of  the  latter  have 
disappeared.  Each  species  appears  to  have  its  own  life- 
period,  its  commencement,  its  culmination,  and  its  gradual 
decay ;  and  the  life-periods  of  different  species  may  be  of  very 
different  duration. 

Erom  what  has  been  said  above,  it  may  be  gathered  that 
our  existing  species  of  animals  and  plants  are,  for  the  most 
part,  quite  of  modem  origin,  using  the  term  '-modern  ';  in  its 
geological  acceptation.  Measured  by  human  standards,  the 
majority  of  existing  animals  (which  are  capable  of  being 
preserved  as  fossils)  are  known  to  have  a  high  antiquity ; 
and  some  of  them  can  boast  of  a  pedigree  which  even  the 
geologist  may  regard  with  respect.  Not  a  few  of  our  shell- 
fish are  known  to  have  commenced  their  existence  at  some 
point  of  the  Tertiary  period;  one  Lampshell  (Tcrcbratulina 


THE   BIOLOGICAL  RELATIONS   OI<    FOSSILS.  59 

caput-strpeiitis)  is  believed  to  have  survived  since  the  Chalk ; 
and  some  of  the  Foraminifera  date,  at  any  rate,  from  the 
Carboniferous  period.  We  learn  from  this  the  additional 
fact  that  our  existing  animals  and  plants  do  not  constitute  an 
assemblage  of  organic  forms  which  were  introduced  into  the 
world  collectively  and  simultaneously,  but  that  they  com- 
menced their  existence  at  very  different  periods,  some  being 
extremely  old,  whilst  others  may  be  regarded  as  compara- 
tively recent  animals.  And  this  introduction  of  the  existing 
fauna  and  flora  was  a  slow  and  gradual  process,  as  shown 
admirably  by  the  study  of  the  fossil  shells  of  the  Tertiaiy 
period.  Thus,  in  the  earlier  Tertiary  period,  we  find  about 
95  per  cent  of  the  known  fossil  shells  to  be  species  that  are 
no  longer  in  existence,  the  remaining  5  per  cent  being 
forms  which  are  known  to  live  in  our  present  seas.  In  the 
middle  of  the  Tertiary  period  we  find  many  more  recent 
and  still  existing  species  of  shells,  and  the  extinct  types  are 
much  fewer  in  number;  and  this  gradual  introduction  of 
forms  now  living  goes  on  steadily,  till,  at  the  close  of  the  Ter- 
tiary period,  the  proportions  with  which  we  started  may  be 
reversed,  as  many  as  90  or  95  per  cent  of  the  fossil  shells 
being  forms  still  alive,  while  not  more  than  5  per  cent  may 
have  disappeared. 

All  known  animals  at  the  present  day  may  be  divided  into 
some  five  or  six  primary  divisions,  which  are  known  technically 
as  " sub-kingdoms"  Each  of  these  sub-kingdoms*  may  be 
regarded  as  representing  a  certain  type  or  plan  of  structure, 
and  all  the  animals  comprised  in  each  are  merely  modified  forms 
of  this  common  type.  Not  only  are  all  known  living  animals 
thus  reducible  to  some  five  or  six  fundamental  plans  of  struc- 
ture, but  amongst  the  vast  series  of  fossil  forms  no  one  has 
yet  been  found  —  however  unlike  any  existing  animal  —  to 
possess  peculiarities  which  would  entitle  it  to  be  placed  in  a 
new  sub-kingdom.  All  fossil  animals,  therefore,  are  capable 
of  being  referred  to  one  or  other  of  the  primary  divisions  of 
the  animal  kingdom.  Many  fossil  groups  have  no  closely- 
related  group  now  in  existence ;  but  in  no  case  do  we  meet 
with  any  grand  structural  type  which  has  not  survived  to  the 
present  day. 

The  old  types  of  life  differ  in  many  respects  from  those  now 
upon  the  earth ;  and  the  further  back  we  pass  in  time,  the 
more  marked  does  this  divergence  become.  Thus,  if  we  were 
to  compare  the  animals  which  lived  in  the  Silurian  seas  with 

*  In  the  Appendix  a  brief  definition  is  given  of  the  sub-kingdoms,  and 
the  chief  divisions  of  each  are  enumerated. 


60  PRINCIPLES   OF   PALAEONTOLOGY. 

those  inhabiting  our  present  oceans,  we  should  in  most  in- 
stances find  differences  so  great  as  almost  to  place  us  in 
another  world.  This  divergence  is  the  most  marked  in  the 
Palaeozoic  forms  of  life,  less  so  in  those  of  the  Mesozoic  period, 
and  less  still  in  the  Tertiary  period.  Each  successive  formation 
has  therefore  presented  us  with  animals  becoming  gradually 
more  and  more  like  those  now  in  existence ;  and  though  there 
is  an  immense  and  striking  difference  between  the  Silurian 
animals  and  those  of  to-day,  this  difference  is  greatly  reduced 
if  we  compare  the  Silurian  fauna  with  the  Devonian ;  that 
again  with  the  Carboniferous  \  and  so  on  till  we  reach  the 
present. 

It  follows  from  the  above  that  the  animals  of  any  given 
formation  are  more  like  those  of  the  next  formation  below, 
and  of  the  next  formation  above,  than  they  are  to  any  others ; 
and  this  fact  of  itself  is  an  almost  inexplicable  one,  unless  we 
believe  that  the  animals  of  any  given  formation  are,  in  part  at 
any  rate,  the  lineal  descendants  of  the  animals  of  the  preced- 
ing formation,  and  the  progenitors,  also  in  part  at  least,  of  the 
animals  of  the  succeeding  formation.  In  fact,  the  palaeon- 
tologist is  so  commonly  confronted  with  the  phenomenon  of 
closely-allied  forms  of  animal  life  succeeding  one  another  in 
point  of  time,  that  he  is  compelled  to  believe  that  such  forms 
have  been  developed  from  some  common  ancestral  type  by 
some  process  of  "evolution"  On  the  other  hand,  there  are 
many  phenomena,  such  as  the  apparently  sudden  introduction 
of  new  forms  throughout  all  past  time,  and  the  common  occur- 
rence of  wholly  isolated  types,  which  cannot  be  explained  in 
this  way.  Whilst  it  seems  certain,  therefore,  that  many  of  the 
phenomena  of  the  succession  of  animal  life  in  past  periods  can 
only  be  explained  by  some  law  of  evolution,  it  seems  at  the 
same  time  certain  that  there  has  always  been  some  other 
deeper  and  higher  law  at  work,  on  -the  nature  of  which  it 
would  be  futile  to  speculate  at  present. 

Not  only  do  we  find  that  the  animals  of  each  successive 
formation  become  gradually  more  and  more  like  those  now 
existing  upon  the  globe,  as  we  pass  from  the  older  rocks  into 
the  newer,  but  we  also  find  that  there  has  been  a  gradual  pro- 
gression and  development  in  the  types  of  animal  life  which 
characterise  the  geological  ages.  If  we  take  the  earliest-known 
and  oldest  examples  of  any  given  group  of  animals,  it  can 
sometimes  be  shown  that  these  primitive  forms,  though  in 
themselves  highly  organised,  possessed  certain  characters  such 
as  are  now  only  seen  in  \\\Q  young  of  their  existing  representa- 
tives. In  technical  language,  the  early  forms  of  life  in  some 


THE   BIOLOGICAL   RELATIONS   OF   FOSSILS.          6 1 

instances  possess  "embryonic"  characters,  though  this  does 
not  prevent  them  often  attaining  a  size  much  more  gigantic 
than  their  nearest  living  relatives.  Moreover,  the  ancient 
forms  of  life  are  often  what  is  called  "  comprehensive  types  " 
—that  is  to  say,  they  possess  characters  in  combination  such 
as  we  nowadays  only  find  separately  developed  in  different 
groups  of  animals.  Now,  this  permanent  retention  of  embry- 
onic characters  and  this  "comprehensiveness"  of  structural 
type  are  signs  of  what  a  zoologist  considers  to  be  a  compara- 
tively low  grade  of  organisation ;  and  the  prevalence  of  these 
features  in  the  earlier  forms  of  animals  is  a  very  striking  phe- 
nomenon, though  they  are  none  the  less  perfectly  organised  so 
far  as  their  own  type  is  concerned.  As  we  pass  upwards  in 
the  geological  scale,  we  find  that  these  features  gradually  dis- 
appear, higher  and  ever  higher  forms  are  introduced,  and 
"  specialisation  "  of  type  takes  the  place  of  the  former  com- 
prehensiveness. We  shall  have  occasion  to  notice  many  of 
the  facts  on  which  these  views  are  based  at  a  later  period,  and 
in  connection  with  actual  examples.  In  the  meanwhile,  it  is 
sufficient  to  state,  as  a  widely-accepted  generalisation  of  palae- 
ontology, that  there  has  been  in  the  past  a  general  progression 
of  organic  types,  and  that  the  appearance  of  the  lower  forms 
of  life  has  in  the  main  preceded  that  of  the  higher  forms  in 
point  of  time. 


PART     II. 


HISTORICAL    PALEONTOLOGY. 


PART    II. 


CHAPTER     VII. 
THE  LAURENTIAN  AND  HURONIAN  PERIODS. 

THE  Laurentian  Rocks  constitute  the  base  of  the  entire  strati- 
fied series,  and  are,  therefore,  the  oldest  sediments  of  which 
we  have  as  yet  any  knowledge.  They  are  more  largely  and 
more  typically  developed  in  North  America,  and  especially  in 
Canada,  than  in  any  known  part  of  the  world,  and  they  derive 
their  title  from  the  range  of  hills  which  the  old  French  geo- 
graphers named  the  "  Laurentides."  These  hills  are  com- 
posed of  Laurentian  Rocks,  and  form  the  watershed  between 
the  valley  of  the  St  Lawrence  river  on  the  one  hand,  and  the 
great  plains  which  stretch  northwards  to  Hudson  Bay  on  the 
other  hand.  The  main  area  of  these  ancient  deposits  forms 
a  great  belt  of  rugged  and  undulating  country,  which  extends 
from  Labrador  westwards  to  Lake  Superior,  and  then  bends 
northwards  towards  the  Arctic  Sea.  Throughout  this  extensive 
area  the  Laurentian  Rocks  for  the  most  part  present  themselves 
in  the  form  of  low,  rounded,  ice-worn  hills,  which,  if  generally 
wanting  in  actual  sublimity,  have  a  certain  geological  grandeur 
from  the  fact  that  they  "have  endured  the  battles  and  the  storms 
of  time  longer  than  any  other  mountains"  (Dawson).  In  some 
places,  however,  the  Laurentian  Rocks  produce  scenery  of  the 
most  magnificent  character,  as  in  the  great  gorge  cut  through 
them  by  the  river  Saguenay,  where  they  rise  at  times  into  ver- 
tical precipices  1500  feet  in  height.  In  the  famous  group  of 
the  Adirondack  mountains,  also,  in  the  state  of  New  York, 
they  form  elevations  no  less  than  6000  feet  above  the  level  of 
the  sea.  As  a  general  rule,  the  character  of  the  Laurentian 
region  is  that  of  a  rugged,  rocky,  rolling  country,  often  densely 


66  HISTORICAL   PALEONTOLOGY. 

timbered,  but  rarely  well  fitted  for  agriculture,  and  chiefly 
attractive  to  the  hunter  and  the  miner. 

As  regards  its  mineral  characters,  the  Laurentian  series  is 
composed  throughout  of  metamorphic  and  highly  crystalline 
rocks,  which  are  in  a  high  degree  crumpled,  folded,  and 
faulted.  By  the  late  Sir  William  Logan  the  entire  series  was 
divided  into  two  great  groups,  the  Lower  Laurentian  and  the 
Upper  Laurentian,  of  which  the  latter  rests  unconformably 
upon  the  truncated  edges  of  the  former,  and  is  in  turn  uncon- 
formably overlaid  by  strata  of  Huronian  and  Cambrian  age 
(fig.  20). 

The  Loiver  Laurentian  series  attains  the  enormous  thickness  of 


a  b 

Fig.  20. — Diagrammatic  section  of  the  Laurentian  Rocks  in  Lower  Canada,  a  Lower 
Laurentian  ;  b  Upper  Laurentian,  resting  unconformably  upon  the  lower  series  ;  c  Cam- 
brian strata  (Potsdam  Sandstone),  resting  unconformably  on  the  Upper  Laurrentian. 

over  20,000  feet,  and  is  composed  mainly  of  great  beds  of  gneiss, 
altered  sandstones  (quartzites),  mica-schist,  hornblende-schist, 
magnetic  iron-ore,  and  haematite,  together  with  masses  of  lime- 
stone. The  limestones  are  especially  interesting,  and  have  an 
extraordinary  development — three  principal  beds  being  known, 
of  which  one  is  not  less  than  1500  feet  thick;  the  collective 
thickness  of  the  whole  being  about  3500  feet. 

The  Upper  Laurentian  series,  as  before  said,  reposes  uncon- 
formably upon  the  Lower  Laurentian,  and  attains  a  thickness 
of  at  least  10,000  feet.  Like  the  preceding,  it  is  wholly  meta- 
morphic, and  is  composed  partly  of  masses  of  gneiss  and  quartz- 
ite  ;  but  it  is  especially  distinguished  by  the  possession  of  great 
beds  of  felspathic  rock,  consisting  principally  of  "  Labrador 
felspar." 

Though  typically  developed  in  the  great  Canadian  area 
already  spoken  of,  the  Laurentian  Rocks  occur  in  other  locali- 
ties, both  in  America  and  in  the  Old  World.  In  Britain,  the 
so-called  "  fundamental  gneiss  "  of  the  Hebrides  and  of  Suther- 
landshire  is  probably  of  Lower  Laurentian  age,  and  the  "  hy- 
persthene  rocks  "  of  the  Isle  of  Skye  may,  with  great  proba- 
bility, be  regarded  as  referable  to  the  Upper  Laurentian.  In 
other  localities  in  Great  Britain  (as  in  St  David's,  South 
Wales ;  the  Malvern  Hills ;  and  the  North  of  Ireland)  occur 
ancient  metamorphic  deposits  which  also  are  probably  refer- 
able to  the  Laurentian  series.  The  so-called  "  primitive  gneiss" 
of  Norway  appears  to  belong  to  the  Laurentian,  and  the 


THE   LAURENTIAN   AND   HURONIAN    PERIODS.      6/ 


ancient  metamorphic  rocks  of  Bohemia  and  Bavaria  may  be 
regarded  as  being  approximately  of  the  same  age. 

By  some  geological  writers  the  ancient  and  highly  meta- 
morphosed sediments  of  the  Laurentian  and  the  succeeding 
Huronian  series  have  been  spoken  of  as  the  "  Azoic  rocks  " 
(Gr.  a,  without ;  zoe,  life) ;  but  even  if  we  were  wholly  destitute 
of  any  evidence  of  life  during  these  periods,  this  name  would  be 
objectionable  upon  theoretical  grounds.  If  a  general  name  be 
needed,  that  of  "  Eozoic  "  (Gr.  eos,  dawn  ;  zoe,  life),  proposed 
by  Principal  Dawson,  is  the  most  appropriate.  Owing  to  their 
metamorphic  condition,  geologists  long  despaired  of  ever  de- 
tecting any  traces  of  life  in  the  vast  pile  of  strata  which  con- 
stitute the  Laurentian  System.  Even  before  any  direct  traces 
were  discovered,  it  was,  however,  pointed  out  that  there  were 
good  reasons  for  believing  that  the  Laurentian  seas  had  been 
tenanted  by  an  abundance  of  living  beings.  These  reasons 
are  briefly  as  follows  : — (i)  Firstly,  the  Laurentian  series  con- 
sists, beyond  question,  of  marine  sediments  which  originally 
differed  in  no  essential  respect  from  those  which  were  subse- 
quently laid  down  in  the  Cambrian  or  Silurian  periods.  (2) 
In  all  formations  later  than  the  Laurentian,  any  limestones 
which  are  present  can  be  shown,  with  few  exceptions,  to  be 
organic  rocks,  and  to  be  more  or  less  largely  made  up  of  the 
comminuted  debris  of  marine  or  fresh- water  animals.  The 
Laurentian  limestones,  in  consequence  of  the  metamorphism 
to  which  they  have  been  subjected,  are  so  highly  crystalline 
(fig.  21)  that  the  microscope  fails  to  detect  any  organic  struc- 
ture in  the  rock,  and  no  fos- 
sils beyond  those  which  will 
be  spoken  of  immediately  have 
as  yet  been  discovered  in 
them.  We  know,  however,  of 
numerous  cases  in  which  lime- 
stones, of  later  age,  and  un- 
doubtedly organic  to  begin 
with,  have  been  rendered  so 
intensely  crystalline  by  meta- 
morphic action  that  all  traces 
of  organic  structure  have  been 
obliterated.  We  have  there- 
fore, by  analogy,  the  strongest 
possible  ground  for  believing 
that  the  vast  beds  of  Lauren- 
tian limestone  have  been  ori- 
ginally organic  in  their  origin, 
and  primitively  composed,  in  the  main,  of  the  calcareous  skele- 


Fig.  21. — Section  of  Lower  Laurentian 
Limestone  from  Hull,  Ottawa;  enlarged 
five  diameters.  The  rock  is  very  highly 
crystalline,  and  contains  mica  and  other 
minerals.  The  irregular  black  masses  in 
it  are  graphite.  (Original.) 


68  HISTORICAL   PALEONTOLOGY. 

tons  of  marine  animals.  It  woiiid,  in  fact,  be  a  matter  of 
great  difficulty  to  account  for  the  formation  of  these  great  cal- 
careous masses  on  any  other  hypothesis.  (3)  The  occurrence  of 
phosphate  of  lime  in  the  Laurentian  Rocks  in  great  abundance, 
and  sometimes  in  the  form  of  irregular  beds,  may  very  possibly 
be  connected  with  the  former  existence  in  the  strata  of  the  re- 
mains of  marine  animals  of  whose  skeleton  this  mineral  is  a  con- 
stituent. (4)  The  Laurentian  Rocks  contain  a  vast  amount  of 
carbon  in  the  form  of  black-lead  or  graphite.  This  mineral  is 
especially  abundant  in  the  limestones,  occurring  in  regular  beds, 
in  veins  or  strings,  or  disseminated  through  the  body  of  the  lime- 
stone in  the  shape  of  crystals,  scales,  or  irregular  masses.  The 
amount  of  graphite  in  some  parts  of  the  Lower  Laurentian  is 
so  great  that  it  has  been  calculated  as  equal  to  the  quantity  of 
carbon  present  in  an  equal  thickness  of  the  Coal-measures. 
The  general  source  of  solid  carbon  in  the  crust  of  the  earth 
is,  however,  plant-life;  and  it  seems  impossible  to  account  for 
the  Laurentian  graphite,  except  upon  the  supposition  that  it 
is  metamorphosed  vegetable  matter.  (5)  Lastly,  the  great 
beds  of  iron-ore  (peroxide  and  magnetic  oxide)  which  occur 
in  the  Laurentian  series  interstratified  with  the  other  rocks, 
point  with  great  probability  to  the  action  of  vegetable  life; 
since  similar  deposits  in  later  formations  can  commonly  be 
shown  to  have  been  formed  by  the  deoxidising  power  of  vege- 
table matter  in  a  state  of  decay. 

In  the  words  of  Principal  Dawson,  "  any  one  of  these  rea- 
sons might,  in  itself,  be  held  insufficient  to  prove  so  great  and, 
at  first  sight,  unlikely  a  conclusion  as  that  of  the  existence  of 
abundant  animal  and  vegetable  life  in  the  Laurentian ;  but  the 
concurrence  of  the  whole  in  a  series  of  deposits  unquestion- 
ably marine,  forms  a  chain  of  evidence  so  powerful  that  it 
might  command  belief  even  if  no  fragment  of  any  organic  or 
living  form  or  structure  had  ever  been  recognised  in  these  an- 
cient rocks."  Of  late  years,  however,  there  have  been  dis- 
covered in  the  Laurentian  Rocks  certain  bodies  which  are 
believed  to  be  truly  the  remains  of  animals,  and  of  which  by 
far  the  most  important  is  the  structure  known  under  the  now 
celebrated  name  of  Eozoon.  If  truly  organic,  a  very  special 
and  exceptional  interest  attaches  itself  to  Eozoon,  as  being  the 
most  ancient  fossil  animal  of  which  we  have  any  knowledge ; 
but  there  are  some  who  regard  it  really  a  peculiar  form  of 
mineral  structure,  and  a  severe,  protracted,  and  still  unfinished 
controversy  has  been  carried  on  as  to  its  nature.  Into  this 
controversy  it  is  wholly  unnecessary  to  enter  here  ;  and  it  will 
be  sufficient  to  briefly  explain  the  structure  of  Eozob'n,  as  eluci- 
dated by  the  elaborate  and  masterly  investigations  of  Car- 


THE   LAURENTIAN   AND   HURONIAN   PERIODS.      69 

penter  and  Dawson,  from  the  standpoint  that  it  is  a  genuine 
organism — the  balance  of  evidence  up  to  this  moment  inclin- 
ing decisively  to  this  view. 

The  structure  known  as  Eozoon  is  found  in  various  localities 
in  the  Lower  Laurentian  limestones  of  Canada,  in  the  form  of 
isolated  masses  or  spreading  layers,  which  are  composed  of 
thin  alternating  laminae,  arranged  more  or  less  concentrically 
(fig.  22).  The  laminae  of  these  masses  are  usually  of  different 


Fig.  22. — Fragment  of  Eozoon,  of  the  natural  size,  showing  alternate  laminie 
ot  loganite  and  dolomite.     (After  Dawson.) 

colours  and  composition  ;  one  series  being  white,  and  com- 
posed of  carbonate  of  lime — whilst  the  laminae  of  the  second 
series  alternate  with  the  preceding,  are  green  in  colour,  and 
are  found  by  chemical  analysis  to  consist  of  some  silicate, 
generally  serpentine  or  the  closely-related  "  loganite."  In 
some  instances,  however,  all  the  laminae  are  calcareous,  the 
concentric  arrangement  still  remaining  visible  in  consequence 
of  the  fact  that  the  laminae  are  composed  alternately  of  lighter 
and  darker  coloured  limestone. 

When  first  discovered,  the  masses  of  Eozoon  were  supposed 
to  be  of  a  mineral  nature ;  but  their  striking  general  resem- 
blance to  the  undoubted  fossils  which  will  be  subsequently 
spoken  of  under  the  name  of  Stromatopora  was  recognised  by 
Sir  William  Logan,  and  specimens  were  submitted  for  minute 
examination,  first  to  Principal  Dawson,  and  subsequently  to 
Dr  W.  B.  Carpenter.  After  a  careful  microscopic  examina- 
tion, these  two  distinguished  observers  came  to  the  conclusion 
that  Eozoon  was  truly  organic,  and  in  this  opinion  they  were 
afterwards  corroborated  by  other  high  authorities  (Mr  W.  K. 
Parker,  Profesor  Rupert  Jones,  Mr  H.  B.  Brady,  Professor 
Giimbel,  &c.)  Stated  briefly,  the  structure  of  Eozoon,  as  ex- 
hibited by  the  microscope,  is  as  follows  : — 


HISTORICAL   PALAEONTOLOGY. 


...  b 


Fig.  23. — Diagram  of  a  portion  of  Eozoon  cut  verti- 
cally. A,  B,  C,  Three  tiers  of  chambers  communicating 
with  one  another  by  slightly  constricted  apertures  :  a  a, 
The  true  shell-wall,  perforated  by  numerous  delicate 
tubes;  b  b,  The  main  calcareous  skeleton  ("intermedi- 
ate skeleton");  c,  Passage  of  communication  (" stolon- 
passage  ")  from  one  tier  of  chambers  to  another  ;  </,  Rami- 


The concentrically-laminated  mass  of  Eozoon  is  composed 
of  numerous  calcareous  layers,  representing  the  original  skele- 
ton of  the  organism  (fig.  23,  b).  These  calcareous  layers  serve 

to  separate  and  de- 
fine a  series  of  cham- 
bers arranged  in  suc- 
cessive tiers,  one 
above  the  other  (fig. 
23,  A,  B,  C)  ;  and 
they  are  perforated 
not  only  by  passages 
(fig.  23,  c\  which 
serve  to  place  suc- 
cessive tiers  of  cham- 
bers in  communica- 
tion, but  also  by  a 
system  of  delicate 
branching  canals  (fig. 
23,  d\  Moreover, 
the  central  and  prin- 
cipal portion  of  each 
calcareous  layer,  with 
the  ramified  canal- 
system  just  spoken 
of,  is  bounded  both  above  and  below  by  a  thin  lamina  which  has 
a  structure  of  its  own,  and  which  may  be  regarded  as  the  proper 
shell-wall  (fig.  23,  a  a).  This  proper  wall  forms  the  actual  lin- 
ing of  the  chambers,  as  well  as  the  outer  surface  of  the  whole 
mass ;  and  it  is  perforated  with  numerous  fine  vertical  tubes 
(fig.  24,  a  a),  opening  into  the  chambers  and  on  to  the  sur- 
face by  corresponding  fine  pores.  From  the  resemblance  of 
this  tubulated  layer  to  similar  structures  in  the  shell  of  the 
Nummulite,  it  is  often  spoken  of  as  the  "  Nummuline  layer." 
The  chambers  are  sometimes  piled  up  one  above  the  other  in 
an  irregular  manner ;  but  they  are  more  commonly  arranged 
in  regular  tiers,  the  separate  chambers  being  marked  off  from 
one  another  by  projections  of  the  wall  in  the  form  of  parti- 
tions, which  are  so  far  imperfect  as  to  allow  of  a  free  communi- 
cation between  contiguous  chambers.  In  the  original  condi- 
tion of  the  organism,  all  these  chambers,  of  course,  must  have 
been  filled  with  living  matter;  but  they  are  found  in  the  present 
state  of  the  fossil  to  be  generally  filled  with  some  silicate,  such 
as  serpentine,  which  not  only  fills  the  actual  chambers,  but  has 
also  penetrated  the  minute  tubes  of  the  proper  wall  and  the 
branching  canals  of  the  intermediate  skeleton.  In  some  cases 


fying  tubes   in    the   calcareous   skeleton, 
penter  ) 


(After  Car- 


THE   LAURENTIAN   AND   HURONIAN    PERIODS.      ;i 

the  chambers  are  simply  filled  with  crystalline  carbonate  of 
lime.     When  the  originally  porous  fossil  has  been  permeated 


Fij.  24. — Portion  of  one  of  the  calcareous  layers  of  Eozofin,  magnified  100  diameters. 
a  a,  The  proper  wall  ("  Nummuline  layer  ")  of  one  of  the  chambers,  showing  the  fine  ver- 
tical tubuli  with  which  it  is  penetrated,  and  which  are  slightly  bent  along  the  line  a'  a' . 
c  c,  The  intermediate  skeleton,  with  numerous  branched  canals.  The  oblique  lines  are 
the  cleavage  planes  of  the  carbcnite  of  lime,  extending  across  both  the  intermediate 
skeleton  and  the  proper  wall.  (After  Carpenter.) 

by  a  silicate,  it  is  possible  to  dissolve  away  the  whole  of  the 
calcareous  skeleton  by  means  of  acids,  leaving  an  accurate  and 
beautiful  cast  of  the  chambers  and  the  tubes  connected  with 
them  in  the  insoluble  silicate. 

The  above  are  the  actual  appearances  presented  by  Eozoon 
when  examined  microscopically,  and  it  remains  to  see  how 
far  they  enable  us  to  decide  upon  its  true  position  in  the 
animal  kingdom.  Those  who  wish  to  study  this  interesting 
subject  in  detail  must  consult  the  admirable  memoirs  by  Dr 
W.  B.  Carpenter  and  Principal  Dawson :  it  will  be  enough 
here  to  indicate  the  results  which  have  been  arrived  at.  The 
only  animals  at  the  present  day  which  possess  a  continuous 
calcareous  skeleton,  perforated  by  pores  and  penetrated  by 
canals,  are  certain  organisms  belonging  to  the  group  of  the 
Foraminifera.  We  have  had  occasion  before  to  speak  of  these 
animals,  and  as  they  are  not  conspicuous  or  commonly-known 
forms  of  life,  it  may  be  well  to  say  a  few  words  as  to  the 
structure  of  the  living  representatives  of  the  group.  The 
Foraminifera  are  all  inhabitants  of  the  sea,  and  are  mostly  of 
small  or  even  microscopic  dimensions.  Their  bodies  are  com- 


72  HISTORICAL   PALEONTOLOGY. 

posed  of  an  apparently  structureless  animal  substance  of  an 
albuminous  nature  ("  sarcode "),  of  a  gelatinous  consistence, 
transparent,  and  exhibiting  numerous  minute  granules  or 
rounded  particles.  The  body-substance  cannot  be  said  in 
itself  to  possess  any  definite  form,  except  in  so  far  as  it  may 
be  bounded  by  a  shell ;  but  it  has  the  power,  wherever  it  may 
be  exposed,  of  emitting  long  thread-like  filaments  ("pseudo- 
podia  "),  which  interlace  with  one  another  to  form  a  network 
(fig.  25,  b).  These  filaments  can  be  thrown  out  at  will,  and 


Fig.  25.— The  animal  of  Nonionina,  one  of  the  Foraminifera,  after  the  shell  has  been 
removed  by  a  weak  acid  ;  b,  Gromta,  a  single-chambered  Foraminifer  (after  Schultze), 
showing  the  shell  surrounded  by  a  network  of  filaments  derived  from  the  body  substance. 

to  considerable  distances,  and  can  be  again  retracted  into  the 
soft  mass  of  the  general  body-substance,  and  they  are  the 
agents  by  which  the  animal  obtains  its  food.  The  soft  bodies 
of  the  Foraminifera  are  protected  by  a  shell,  which  is  usually 
calcareous,  but  may  be  composed  of  sand-grains  cemented 


THE   LAURENTIAN   AND   HUROXIAN    PERIODS.       73 

together;  and  it  may  consist  of  a  single  chamber  (fig.  26,  a), 
or  of  many  chambers  arranged  in  different  ways  (fig.  26,  b-f\ 


Fig.  26. — Shells  of  \\v\ngForatninzfera.  a,  Orbulina  universa,  in  its  perfect  condi- 
tion, showing  the  tubular  spines  which  radiate  from  the  surface  of  the  shell ;  b,  Globi- 
gerina  bulloides,  in  its  ordinary  condition,  the  thin  hollow  spines  which  are  attached  to 
the  shell  when  perfect  having  been  broken  off ;  c,  Textulana  variabilis  ;  d,  Peneroplis 
planatns ',  e,  Rotalia  conca merata  ',  f,  Cristellaria  snbarcuntula.  [Fig.  a  is  after 
Wyville  Thomson  ;  the  others  are  after  Williamson.  All  the  figures  are  greatly  en- 
larged.] 

Sometimes  the  shell  has  but  one  large  opening  into  it — the 
mouth  ;  and  then  it  is  from  this  aperture  that  the  animal  pro- 
trudes the  delicate  net  of  filaments  with  which  it  seeks  its 
food.  In  other  cases  the  entire  shell  is  perforated  with 
minute  pores  (fig.  26,  e),  through  which  the  soft  body-substance 
gains  the  exterior,  covering  the  whole  shell  with  a  gelatinous 
film  of  animal  matter,  from  which  filaments  can  be  emitted  at 
any  point.  When  the  shell  consists  of  many  chambers,  all  of 
these  are  placed  in  direct  communication  with  one  another, 
and  the  actual  substance  of  the  shell  is  often  traversed  by 
minute  canals  filled  with  living  matter  (e.g.,  in  Calcarina  and 
Nummulind).  The  shell,  therefore,  may  be  regarded,  in  such 
cases,  as  a  more  or  less  completely  porous  calcareous  structure, 


74  PRINCIPLES   OF    PALAEONTOLOGY. 

filled  to  its  minutest  internal  recesses  with  the  substance  of  the 
living  animal,  and  covered  externally  with  a  layer  of  the  same 
substance,  giving  off  a  network  of  interlacing  filaments. 

Such,  in  brief,  is  the  structure  of  the  living  Foraminifera; 
and  it  is  believed  that  in  Eozoon  we  have  an  extinct  example 
of  the  same  group,  not  only  of  special  interest  from  its  imme- 
morial antiquity,  but  hardly  less  striking  from  its  gigantic 
dimensions.  In  its  original  condition,  the  entire  chamber- 
system  of  Eozoon  is  believed  to  have  been  filled  with  soft 
structureless  living  matter,  which  passed  from  chamber  to 
chamber  through  the  wide  apertures  connecting  these  cavities, 
and  from  tier  to  tier  by  means  of  the  tubuli  in  the  shell-wall  and 
the  branching  canals  in  the  intermediate  skeleton.  Through 
the  perforated  shell-wall  covering  the  outer  surface  the  soft 
body-substance  flowed  out,  forming  a  gelatinous  investment, 
from  every  point  of  which  radiated  an  interlacing  net  of  deli- 
cate filaments,  providing  nourishment  for  the  entire  colony. 
In  its  present  state,  as  before  said,  all  the  cavities  originally 
occupied  by  the  body-substance  have  been  filled  with  some 
mineral  substance,  generally  with  one  of  the  silicates  of  mag- 
nesia; and  it  has  been  asserted  that  this  fact  militates  strongly 
against  the  organic  nature  of  Eozoon,  if  not  absolutely  dis- 
proving it.  As  a  matter  of  fact,  however — as  previously  no- 
ticed— it  is  by  no  means  very  uncommon  at  the  present  day 
to  find  the  shells  of  living  species  of  Foraminifera  in  which 
all  the  cavities  primitively  occupied  by  the  body-substance, 
down  to  the  minutest  pores  and  canals,  have  been  similarly 
injected  by  some  analogous  silicate,  such  as  glauconite. 

Those,  then,  whose  opinions  on  such  a  subject  deservedly 
carry  the  greatest  weight,  are  decisively  of  opinion  that  we  are 
presented  in  the  Eozoon  of  the  Laurentian  Rocks  of  Canada 
with  an  ancient,  colossal,  and  in  some  respects  abnormal  type 
of  the  Foraminifera.  In  the  words  of  Dr  Carpenter,  it  is  not 
pretended  that  "  the  doctrine  of  the  Foraminiferal  nature  of 
Eozoon  can  be  proved  in  the  demonstrative  sense;"  but  it 
may  be  affirmed  "  that  the  convergence  of  a  number  of  separate 
and  independent  probabilities,  all  accordant  with  that  hypothesis, 
while  a  separate  explanation  must  be  invented  for  each  of 
them  on  any  other  hypothesis,  gives  it  that  high  probability 
on  which  we  rest  in  the  ordinary  affairs  of  life,  in  the  verdicts 
of  juries,  and  in  the  interpretation  of  geological  phenomena 
generally." 

It  only  remains  to  be  added,  that  whilst  Eozoon  is  by  far 
the  most  important  organic  body  hitherto  found  in  the  Lauren- 
tian, and  has  been  here  treated  at  proportionate  length,  other 


THE   LAURENTIAN   AND   HURONIAN   PERIODS.      75 

traces  of  life  have  been  detected,  which  mny  subsequently 
prove  of  great  interest  and  importance.  Thus,  Principal 
Davvson  has  recently  described  under  the  name  of  Arch&o- 
sphcerina  certain  singular  rounded  bodies  which  he  has  dis- 
covered in  the  Laurentian  limestones,  and  which  he  believes 
to  be  casts  of  the  shells  of  Foraminifera  possibly  somewhat 
allied  to  the  existing  Globigerina.  The  same  eminent  palaeon- 
tologist has  also  described  undoubted  worm -burrows  from 
rocks  probably  of  Laurentian  age.  Further  and  more  extend- 
ed researches,  we  may  reasonably  hope,  will  probably  bring 
to  light  other  actual  remains  of  organisms  in  these  ancient 
deposits. 

THE  HURONIAN  PERIOD. 

The  so  called  Huronian  Rocks,  like  the  Laurentian,  have 
their  typical  development  in  Canada,  and  derive  their  name 
from  the  fact  that  they  occupy  an  extensive  area  on  the  borders 
of  Lake  Huron.  They  are  wholly  metamorphic,  and  consist 
principally  of  altered  sandstones  or  quartzites,  siliceous,  fels- 
pathic,  or  talcose  slates,  conglomerates,  and  limestones.  They 
are  largely  developed  on  the  north  shore  of  Lake  Superior, 
and  give  rise  to  a  broken  and  hilly  country,  very  like  that 
occupied  by  the  Laurentian s,  with  an  abundance  of  timber, 
but  rarely  with  sufficient  soil  of  good  quality  for  agricultural 
purposes.  They  are,  however,  largely  intersected  by  mineral 
veins,  containing  silver,  gold,  and  other  metals,  and  they  will 
ultimately  doubtless  yield  a  rich  harvest  to  the  miner.  The 
Huronian  Rocks  have  been  identified,  with  greater  or  less 
certainty,  in  other  parts  of  North  America,  and  also  in  the 
Old  World. 

The  total  thickness  of  the  Huronian  Rocks  in  Canada  is 
estimated  as  being  not  less  than  18,000  feet,  but  there  is  con- 
siderable doubt  as  to  their  precise  geological  position.  In 
their  typical  area  they  rest  unconformably  on  the  edges  of 
strata  of  Lower  Laurentian  age  ;  but  they  have  never  been  seen 
in  direct  contact  with  the  Upper  Laurentian,  and  their  exact 
relations  to  this  series  are  therefore  doubtful.  It  is  thus  open 
to  question  whether  the  Huronian  Rocks  constitute  a  distinct 
formation,  to  be  intercalated  in  point  of  time  between  the 
Laurentian  and  the  Cambrian  groups ;  or  whether,  rather,  they 
should  not  be  considered  as  the  metamorphosed  representa- 
tives of  the  Lower  Cambrian  Rocks  of  other  regions. 

As  regards  the  fossils  of  the  Huronian  Rocks,  little  can  be 
said.  Some  of  the  specimens  of  Eozobn  Canadense\\\\\c\\  have 


76  HISTORICAL   PALAEONTOLOGY. 

been  discovered  in  Canada  are  thought  to  come  from  rocks 
which  are  probably  of  Huronian  age.  In  Bavaria,  Dr  Giimbel 
has  described  a  species  of  Eozoon  under  the  name  of  Eozoon 
Bavaricum,  from  certain  metamorphic  limestones  which  he 
refers  to  the  Huronian  formation.  Lastly,  the  late  Mr  Billings 
described,  from  rocks  in  Newfoundland  apparently  referable  to 
the  Huronian,  certain  problematical  limpet-shaped  fossils,  to 
which  he  gave  the  name  of  Aspidella. 

LITERATURE. 

Amongst  the  works  and  memoirs  which  the  student  may  consult  with 
regard  to  the  Lauren tuui  and  Huronian  deposits  may  be  mentioned  the 
following  :* — 

(1)  'Report  of  Progress  of  the  Geological  Survey  of  Canada  from  its 

Commencement  to  1863,'  pp.  38-49,  and  pp.  50-66. 

(2)  'Manual  of  Geology.'     Dana.     2d  Ed.      1875. 

(3)  'The  Dawn  of  Life.'     J.  W.  Dawson.      1876. 

(4)  "  On  the  Occurrence  of  Organic  Remains  in  the  Laurentian  Rocks 

of  Canada."     Sir  W.   E.  Logan.      'Quart.  Journ.  Geol.  Soc.,' 
xxi.  45-50. 

(5)  "  On  the  Structure  of  Certain  Organic  Remains  in  the  Laurentian 

Limestones  of  Canada."     J.  W.  Dawson.     '  Quart.  Journ.  Geol. 
Soc.,'  xxi.  51-59. 

(6)  "  Additional  Note  on  the  Structure  and  Affinities  of  Eozoon  Cana- 

dense."     W.   B.    Carpenter.      'Quart.  Journ.  Geol.  Soc.,'  xxi. 
59-66. 

(7)  "Supplemental  Notes  on  the  Structure  and  Affinities  of  Eozoon 

Canadense."     \V.   B.   Carpenter.     'Quart.  Journ.   Geol.   Soc., 
xxii.  219-228. 

(8)  "  On  the  So-Called  Eozoonal  Rocks."     King  &  Rowney.     'Quart. 

Journ.  Geol.  Soc.,'  xxii.  185-218. 

(9)  '  Chemical  and  Geological  Essays.'     Sterry  Hunt. 

The  above  list  only  includes  some  of  the  more  important  memoirs  which 
may  be  consulted  as  to  the  geological  and  chemical  features  of  the  Lauren- 
tian and  Huronian  Rocks,  and  as  to  the  true  nature  of  Eozoon.  Those 
who  are  desirous  of  studying  the  later  phases  of  the  controversy  with  re- 
gard to  Eozoon  must  consult  the  papers  of  Carpenter,  Carter,  Dawson, 
King&  Rowney,  Hahn,  and  others,  in  the  '  Quart.  Journ.  of  the  Geological 
Society,'  the  '  Proceedings  of  the  Royal  Irish  Academy,'  the  'Annals  of  Nat- 
ural History,' the  'Geological  Magazine,' &c.  Dr  Carpenter's  'Introduc- 
tion to  the  Study  of  the  Foraminifera  '  should  also  be  consulted. 


*  In  this  and  in  all  subsequently  following  bibliographical  lists,  not  only 
is  the  selection  of  works  and  memoirs  quoted  necessarily  extremely  limited  ; 
but  only  such  have,  as  a  general  rule,  been  chosen  for  mention  as  are  easily 
accessible  to  students  who  are  in  the  position  of  being  able  to  refer  to  a 
good  library.  Exceptions,  however,  are  occasionally  made  to  this  rule, 
in  favour  of  memoirs  or  works  of  special  historical  interest.  It  is  also  un- 
necessary to  add  that  it  has  not  been  thought  requisite  to  insert  in  these 
lists  the  well-known  handbooks  of  geological  and  pala.'ontolooical  science, 
except  in  such  instances  as  where  they  contain  special  information  on 
special  points. 


THE   CAMBRIAN    PERIOD.  77 

CHAPTER    VIII. 
THE   CAMBRIAN  PERIOD. 

The  traces  of  life  in  the  Laurentian  period,  as  we  have  seen, 
are  but  scanty ;  but  the  Cambrian  Rocks — so  called  from  their 
occurrence  in  North  Wales  and  its  borders  ("  Cambria") — have 
yielded  numerous  remains  of  animals  and  some  dubious  plants. 
The  Cambrian  deposits  have  thus  a  special  interest  as  being 
the  oldest  rocks  in  which  occur  any  number  of  well-preserved 
and  unquestionable  organisms.  We  have  here  the  remains  of 
the  first  fauna,  or  assemblage  of  animals,  of  which  we  have  at 
present  knowledge.  As  regards  their  geographical  distribu- 
tion, the  Cambrian  Rocks  have  been  recognised  in  many  parts 
of  the  world,  but  there  is  some  question  as  to  the  precise  limits 
of  the  formation,  and  we  may  consider  that  their  most  typical 
area  is  in  South  Wales,  where  they  have  been  carefully  worked 
out,  chiefly  by  Dr  Henry  Hicks.  In  this  region,  in  the  neigh- 
bourhood of  the  promontory  of  St  David's,  the  Cambrian  Rocks 
are  largely  developed,  resting  upon  an  ancient  ridge  of  Pre- 
Cambrian  (Laurentian?)  strata,  and  overlaid  by  the  lowest 
beds  of  the  Lower  Silurian.  The  subjoined  sketch-section 
(fig.  27)  exhibits  in  a  general  manner  the  succession  of  strata 
in  this  locality. 

From  this  section  it  will  be  seen  that  the  Cambrian 
Rocks  in  Wales  are  divided  in  the  first  place  into  a  lower  and 
an  upper  group.  The  Lower  Cambrian  is  constituted  at  the 
base  by  a  great  series  of  grits,  sandstones,  conglomerates,  and 
slates,  which  are  known  as  the  "  Longmynd  group,"  from  their 
vast  development  in  the  Longmynd  Hills  in  Shropshire,  and 
which  attain  in  North  Wales  a  thickness  of  8000  feet  or  more. 
The  Longmynd  beds  are  succeeded  by  the  so-called  "  Mene- 
vian  group,"  a  series  of  sandstones,  flags,  and  grits,  about  600 
feet  in  thickness,  and  containing  a  considerable  number  of 
fossils.  The  Upper  Cambrian  series  consists  in  its  lower  por- 
tion of  nearly  5000  feet  of  strata,  principally  shaly  and  slaty, 
which  are  known  as  the  "Lingula  Flags/'  from  the  great 
abundance  in  them  of  a  shell  referable  to  the  genus  Lingula. 
These  are  followed  by  1000  feet  of  dark  shales  and  flaggy 
sandstones,  which  are  known  as  the  "  Tremadoc  slates,"  from 
their  occurrence  near  Tremadoc  in  North  Wales  ;  and  these 
in  turn  are  surmounted,  apparently  quite  conformably,  by  the 
basement  beds  of  the  Lower  Silurian. 
7  ' 


HISTORICAL   PALAEONTOLOGY. 


GENERALISED  SECTION  OF  THE  CAMBRIAN  ROCKS  IN  WALES. 

Fig.  27. 

Arenig  Group  (Base  of  the 
Lower  Silurian). 


Tremacloc  Slates. 

Upper  Lingula  Flags. 

Middle  Lingula  Flags. 

Lower  Lingula  Flags. 
Menevian  Group. 


.....   LongmyndorllarlechGroup. 


Pre-Cambrian  Rocks. 


The  above  may  be  regarded  as  giving  a  typical  series  of  the 
Cambrian  Rocks  in  a  typical  locality ;  but  strata  of  Cambrian 
age  are  known  in  many  other  regions,  of  which  it  is  only 
possible  here  to  allude  to  a  few  of  the  most  important.  In 
Scandinavia  occurs  a  well-developed  series  of  Cambrian  de- 
posits, representing  both  the  lower  and  upper  parts  of  the 


THE   CAMBRIAN   PERIOD. 


79 


formation.  In  Bohemia,  the  Upper  Cambrian,  in  particular, 
is  largely  developed,  and  constitutes  the  so-called  "  Primordial 
zone"  of  Barrande.  Lastlyf  in  North  America,  whilst  the 
Lower  Cambrian  is  only  imperfectly  developed,  or  is  repre- 
sented by  the  Huronian,  the  Upper  Cambrian  formation  has 
a  wide  extension,  containing  fossils  similar  in  character  to  the 
analogous  strata  in  Europe,  and  known  as  the  "  Potsdam  Sand- 
stone." The  subjoined  table  shows  the  chief  areas  where  Cam- 
brian Rocks  are  developed,  and  their  general  equivalency  : 

TABULAR  VIEW  OF  THE  CAMBRIAN  FORMATION. 


Britain, 

Europe. 

America. 

(a.  Tremadoc  Slates. 

a.  Primordial  zone 

a.  Potsdam 

of  Bohemia. 

Sandstone. 

b.  Linjnila  Flags. 

b.  Paradoxides 

b.  Acadian 

Cambrian.    ] 

Schists,  Olenus 
Schists,  and  Dict- 

group  of  New 
Brunswick. 

yonema  schists  of 

I 

Sweden. 

'a.  Longmynd  Beds. 

a.  Fucoidal  Sand- 

Huronian 

stone  of  Sweden. 

Formation  ? 

b.  Llanberis  Slates. 

b,  Eophyton  Sand- 

stone of  Sweden. 

c.  Harlech  Grits. 

Lower        , 
Cambrian. 

d.  Oldhamia     Slates 
of  Ireland. 

e.  Conglomerates  and 

Sandstones       of 

Sutherlandshire  ? 

f.  Menevian  Beds. 

Like  all  the  older  Palaeozoic  deposits,  the  Cambrian  Rocks, 
though  by  no  means  necessarily  what  would  be  called  actually 
"  metamorphic,"  have  been  highly  cleaved,  and  otherwise 
altered  from  their  original  condition.  Owing  partly  to  their 
indurated  state,  and  partly  to  their  great  antiquity,  they  are 
usually  found  in  the  heart  of  mountainous  districts,  which  have 
undergone  great  disturbance,  and  have  been  subjected  to  an 
enormous  amount  of  denudation.  In  some  cases,  as  in  the 
Longmynd  Hills  in  Shropshire,  they  form  low  rounded  eleva- 
tions, largely  covered  by  pasture,  and  with  few  or  no  elements 
of  sublimity.  In  other  cases,  however,  they  rise  into  bold  and 
rugged  mountains,  girded  by  precipitous  clifTs.  Industrially, 
the  Cambrian  Rocks  are  of  interest,  if  only  for  the  reason  that 
the  celebrated  Welsh  slates  of  Llanberis  are  derived  from 
highly-cleaved  beds  of  this  age.  Taken  as  a  whole,  the  Cam- 
brian formation  is  essentially  Composed  of  arenaceous  and 


80  HISTORICAL   PALAEONTOLOGY. 

muddy  sediments,  the  latter  being  sometimes  red,  but  more 
commonly  nearly  black  in  colour.  It  has  often  been  supposed 
that  the  Cambrians  are  a  deep-tea  deposit,  and  that  we  may 
thus  account  for  the  few  fossils  contained  in  them ;  but  the 
paucity  of  fossils  is  to  a  large  extent  imaginary,  and  some  of 
the  Lower  Cambrian  beds  of  the  Longrnynd  Hills  would  ap- 
pear to  have  been  laid  down  in  shallow  water,  as  they  exhibit 
rain-prints,  sun-Cracks,  and  ripple-marks — incontrovertible  evi- 
dence of  their  having  been  a  shore-deposit.  The  occurrence 
of  innumerable  worm-tracks  and  burrows  in  many  Cambrian 
strata  is  also  a  proof  of  shallow-water  conditions  ;  and  the  gen- 
eral absence  of  limestones,  coupled  with  the  coarse  mechani- 
cal nature  of  many  of  the  sediments  of  the  Lower  Cambrian, 
may  be  taken  as  pointing  in  the  same  direction. 

The  life  of  the  Cambrian,  though  not  so  rich  as  in  the  suc- 
ceeding Silurian  period,  nevertheless  consists  of  representa- 
tives of  most  of  the  great  classes  of  invertebrate  animals.  The 
coarse  sandy  deposits  of  the  formation,  which  abound  more 
particularly  towards  its  lower  part,  naturally  are  to  a  large 
extent  barren  of  fossils ;  but  the  muddy  sediments,  when  not 
too  highly  cleaved,  and  especially  towards  the  summit  of  the 
group,  are  replete  with  organic  remains.  This  is  also  the  case,  in 
many  localities  at  any  rate,  with  the  finer  beds  of  the  Potsdam 
Sandstone  in  America.  Limestones  are  known  to  occur  in 
only  a  few  areas  (chiefly  in  America),  and  this  may  account  for 
the  apparent  total  absence  of  corals.  It  is,  however,  interest- 
ing to  note  that,  with  this  exception,  almost  all  the  other  lead- 
ing groups  of  Invertebrates  are  known  to  have  come  into 
existence  during  the  Cambrian  period. 

Of  the  land  -  surfaces  of  the  Cambrian  period  we  know 
nothing ;  and  there  is,  therefore,  nothing  surprising  in  the  fact 
that  our  acquaintance  with  the  Cambrian  vegetation  is  confined 
to  some  marine  plants  or  sea- weeds,  often  of  a  very  obscure  and 
problematical  nature.  The  "  Fucoidal  Sandstone  "  of  Sweden, 
and  the  "  Potsdam  Sandstone  "  of  North  America,  have  both 
yielded  numerous  remains  which  have  been  regarded  as  mark- 
ings left  by  sea-weeds  or  "  Fucoids ;"  but  these  are  highly  enig- 
matical in  their  characters,  and  would,  in  many  instances,  seem 
to  be  rather  referable  to  the  tracks  and  burrows  of  marine 
worms.  The  first-mentioned  of  these  formations  has  also 
yielded  the  curious,  furrowed  and  striated  stems  which  have 
been  described  as  a  kind  of  land-plant  under  the  name  of 
Eophyton  (fig.  28).  It  cannot  be  said,  however,  that  the  vege- 
table origin  of  these  singular  bodies  has  been  satisfactorily 
proved.  Lastly,  there  are  found  in  certain  green  and  purple 


THE  CAMBRIAN    PERIOD.  8 1 

beds  of  Lower  Cambrian  age  at  Bray  Head,  Wicklow,  Ireland, 
some  very  remarkable  fossils,  which  are  well  known  under  the 


Fig.  28.— Fragment  of  Eophyton  Linneanum,  a  supposed  land-p'ant,  Lower 
Cambrian,  Sweden,  of  the  natural  size. 

name  of  Oidhamia,  but  the  true  nature  of  which  is  very  doubtful. 
The  commonest  form  of  Oldhamia  (fig.  29)  consists  of  a 
thread-like  stem  or  axis,  from  which  spring  at  regular  intervals 
bundles  of  short  filamentous  branches  in  a  fan-like  manner. 
In  the  locality  where  it  occurs,  the  fronds  of  Oldhamia  are  very 
abundant,  and  are  spread  over  the  surfaces  of  the  strata  in 
tangled  layers.  That  it  is  organic  is  certain,  and  that  it  is  a 
calcareous  sea-weed  is  probable  ;  but  it  may  possibly  belong  to 
the  sea-mosses  (Poly  zoo) ,  or  to  the  sea-firs  (Sertnlarians). 

Amongst  the  lower  forms  of  animal  life  (Protozoa],  we  find 
the  Sponges  represented  by  the  curious  bodies,  composed  of 
netted  fibres,  to  which  the  name  of  Protospongia  has  been  given 
(fig.  32,  a) ;  and  the  comparatively  gigantic,  conical,  or  cylin- 


HISTORICAL  PALEONTOLOGY. 


Fig.  29. — A  portion  of  Oldhamii  an 
tigiui,  Lower  Cambrian,  Wick  ow,  Ire 
land,  of  the  natural  size.  (After  Salter.) 


drical  fossils  termed  Archceocyathus  by  Mr  Billings  are  certainly 
referable  either  to  the  Foraminifera  or  to  the  Sponges.     The 

almost  total  absence  of  lime- 
stones in  the  formation  may 
be  regarded  as  a  sufficient  ex- 
planation of  the  fact  that  the 
Foraminifera  are  not  more 
largely  and  unequivocally  re- 
presented j  though  the  exist- 
ence of  greensands  in  the 
Cambrian  beds  of  Wisconsin 
and  Tennessee  may  be  taken 
as  an  indication  that  this  class 
of  animals  was  by  no  means 
wholly  wanting.  The  same 
fact  may  explain  the  total  ab- 
sence of  corals,  so  far  as  at 
present  known. 

The  group  of  the  Echinoder- 
mata  (Sea-lilies,  Sea-urchins, 
and  their  allies)  is  represented 
by  a  few  forms,  which  are  prin- 
cipally of  interest  as  being  the  earliest-known  -examples  of  the 
class.  It  is  also  worthy  of  note  that  these  precursors  of  a 
group  which  subsequently  attains  such  geological  importance, 
are  referable  to  no  less  than  three  distinct  orders — the  Crinoids 
or  Sea-lilies,  represented  by  a  species  of  Dendrocrinus ;  the 
Cystideans  by  Protocystitcs ;  and  the  Star-fishes  by  Palasterina 
and  some  other  forms.  Only  the  last  of  these  groups,  how- 
ever, appears  to  occur  in  the  Lower  Cambrian. 

The  Ringed-worms  (Annelida)^  if  rightly  credited  with  all 
the  remains  usually  referred  to  them,  appear  to  have  swarmed 
in  the  Cambrian  seas.  Being  soft-bodied,  we  do  not  find  the 
actual  worms  themselves  in  the  fossil  condition,  but  we  have, 
nevertheless,  abundant  traces  of  their  existence.  In  some 
cases  we  find  vertical  burrows  of  greater  or  less  depth,  often 
expanded  towards  their  apertures,  in  which  the  worm  must 
have  actually  lived  (fig.  30),  as  various  species  do  at  the  pre- 
sent day.  In  these  cases,  the  tube  must  have  been  rendered 
more  or  less  permanent  by  receiving  a  coating  of  mucus,  or 
perhaps  a  genuine  membranous  secretion,  from  the  body  of 
the  animal,  and  it  may  be  found  quite  empty,  or  occupied  by 
a  cast  of  sand  or  mud.  Of  this  nature  are  the  burrows  which 
have  been  described  under  the  names  of  Scolithus  and  Scoleco- 
derma,  and  probably  the  Histioderma  of  the  Lower  Cambrian 


THE  CAMBRIAN    PERIOD.  83 

of  Ireland.     In  other  cases,  as  in  Arenicolites  (fig.  32,  £),  the 
worm  seems  to  have  inhabited  a  double  burrow,  shaped  like 


Fig.  30. — Annelide-burrows  (Scolithus  Hnearis^,  from  the  Potsdam  Sandstone  of 
Canada,  of  the  natural  size.     (After  Billings.) 

the  letter  U,  and  having  two  openings  placed  close  together 
on  the  surface  of  the  stratum.  Thousands  of  these  twin- 
burrows  occur  in  some  of  the  strata  of  the  Longmynd,  and  it 
is  supposed  that  the  worm  used  one  opening  to  the  burrow  as 
an  aperture  of  entrance,  and  the  other  as  one  of  exit.  In  other 
cases,  again,  we  find  simply  the  meandering  trails  caused  by 
the  worm  dragging  its  body  over  the  surface  of  the  mud. 
Markings  of  this  kind  are  commoner  in  the  Silurian  Rocks, 
and  it  is  generally  more  or  less  doubtful  whether  they  may 
not  have  been  caused  by  other  marine  animals,  such  as  shell- 
fish, whilst  some  of  them  have  certainly  nothing  whatever  to 
do  with  the  worms.  Lastly,  the  Cambrian  beds  often  show 
twining  cylindrical  bodies,  commonly  more  or  less  matted 
together,  and  not  confined  to  the  surfaces  of  the  strata,  but 
passing  through  them.  These  have  often  been  regarded  as 
the  remains  of  sea-weeds,  but  it  is  more  probable  that  they 
represent  casts  of  the  underground  burrows  of  worms  of  simi- 
lar habits  to  the  common  lob-worm  (Arenicola)  of  the  present 
day. 

The  Articulate  animals  are  numerously  represented  in  the 
Cambrian  deposits,  but  exclusively  by  the  class  of  Crustaceans. 
Some  of  these  are  little  double-shelled  creatures,  resembling 
our  living  water- fleas  (Ostracoda).  A  few  are  larger  forms,  and 
belong  to  the  same  group  as  the  existing  brine-shrimps  and 
fairy-shrimps  (Phyllopodd).  One  of  the  most  characteristic  of 


84  HISTORICAL  PAL/EON TOLOGY. 

these  is  the  Hymenocaris  vermicauda  of  the  Lingula  Flags  (fig. 
32,  d}.  By  far  the  larger  number  of  the  Cambrian  Crustacea 
belong,  however,  to  the  remarkable  and  wholly  extinct  group 
of  the  Trilobites.  These  extraordinary  animals  must  have 
literally  swarmed  in  the  seas  of  the  later  portion  of  this  and 
the  whole  of  the  succeeding  period;  and  they  survived  in 
greatly  diminished  numbers  till  the  earlier  portion  of  the 
Carboniferous  period.  They  died  out,  however,  wholly  before 
the  close  of  the  Palaeozoic  epoch,  and  we  have  no  Crusta- 
ceans at  the  present  day  which  can  be  considered  as  their 
direct  representatives.  They  have,  however,  relationships  of 
a  more  or  less  intimate  character  with  the  existing  groups  of 
the  Phyllopods,  the  King-crabs  (Limulus],  and  the  Isopods 
("Slaters,"  Wood-lice,  &c.)  Indeed,  one  member  of  the  last- 
mentioned  order,  namely,  the  Scrolls  of  the  coasts  of  Patagonia, 
has  been  regarded  as  the  nearest  living  ally  of  the  Trilobites. 
Be  this  as  it  may,  the  Trilobites  possessed  a  skeleton  which, 
though  capable  of  undergoing  almost  endless  variations,  was 
wonderfully  constant  in  its  pattern  of  structure,  and  we  may 
briefly  describe  here  the  chief  features  of  this. 

The  upper  surface  of  the  body  of  a  Trilobite  was  defended 
by  a  strong  shell  or  "  crust,"  partly  horny  and  partly  calcare- 
ous in  its  composition.  This  shell  (fig.  31)  generally  exhibits 
a  very  distinct  "  trilobation"  or  division  into  three  longitudinal 
lobes,  one  central  and  two  lateral.  It  also  exhibits  a  more 
important  and  more  fundamental  division  into  three  transverse 
portions,  which  are  so  loosely  connected  with  one  another  as 
very  commonly  to  be  found  separate.  The  first  and  most 
anterior  of  these  divisions  is  a  shield  or  buckler  which  covers 
the  head  ;  the  second  or  middle  portion  is  composed  of  mov- 
able rings  covering  the  trunk  ("  thorax  ") ;  and  the  third  is  a 
shield  which  covers  the  tail  or  "  abdomen."  The  head-shield 
(fig.  31,  e)  is  generally  more  or  less  semicircular  in  shape  ;  and 
its  central  portion,  covering  the  stomach  of  the  animal,  is  usu- 
ally strongly  elevated,  and  generally  marked  by  lateral  furrows. 
A  little  on  each  side  of  the  head  are  placed  the  eyes,  which 
are  generally  crescentic  in  shape,  and  resemble  the  eyes  of 
insects  and  many  existing  Crustaceans  in  being  "  compound," 
or  made  up  of  numerous  simple  eyes  aggregated  together. 
So  excellent  is  the  state  of  preservation  of  many  specimens  of 
Trilobites,  that  the  numerous  individual  lenses  of  the  eyes 
have  been  uninjured,  and  as  many  as  four  hundred  have  been 
counted  in  each  eye  of  some  forms.  The  eyes  may  be  sup- 
ported upon  prominences,  but  they  are  never  carried  on  mov- 
able stalks  (as  they  are  in  the  existing  lobsters  and  crabs) ;  and 


THE   CAMBRIAN    PERIOD.  85 

in  some  of  the  Cambrian  Trilobites,  such  as  the  little  Agnosti 
(rig.  31  g),  the  animal  was  blind.     The  lateral  portions  of  the 


Fig.  31.  —  Cambrian  Trilobites:  a,  Paradorides  Bohemicus,  reduced  in  size;  b,  EUip- 
socephalus  Hoffi  ;  c,  Sao  kirsnta  ',  d,  Conocorypke  Snltzeri  (all  the  above,  together  with 
fig.  e,  are  from  the  Upper  Cambrian  or  "Primordial  Zone"  of  Bohemia);  e,  Head-shield 
of  Dikellocephalns  Celticns,  from  the  Lingula  Flags  of  Wales  ;  f,  Head-shield  of  Cono- 
coryphe  Mattheivi,  from  the  Upper  Cambrian  (Acadian  Group)  of  New  Brunswick  ;  g, 
Agnostus  rex,  Bohemia  ;  h,  Tail-shield  of  Dikellocephalus  Minnesotensis,  from  the  Upper 
ambrian  (Potsdam  Sandstone)  of  Minnesota.  After  Barrande  Dawson  Salter  and 


Cambrian  (Potsda 
Dale  Owen.) 


head-shield  are  usually  separated  from  the  central  portion  by 
a  peculiar  line  of  division  (the  so-called  "facial  suture")  on 
each  side  ;  but  this  is  also  wanting  in  some  of  the  Cambrian 
species.  The  backward  angles  of  the  head-shield,  also,  are 
often  prolonged  into  spines,  which  sometimes  reach  a  great 
length.  Following  the  head-shield  behind,  we  have  a  portion 
of  the  body  which  is  composed  of  movable  segments  or  "body- 
rings,"  and  which  is  technically  called  the  "  thorax."  Ordi- 
narily, this  region  is  strongly  trilobed,  and  each  ring  consists  of 
a  central  convex  portion,  and  of  two  flatter  side-lobes.  The 
number  of  body-rings  in  the  thorax  is  very  variable  (from  two 
to  twenty-six),  but  is  fixed  for  the  adult  forms  of  each  group  of 
the  Trilobites.  The  young  forms  have  much  fewer  rings  than 
the  full-grown  ones  ;  and  it  is  curious  to  find  that  the  Cam- 


86  HISTORICAL  PALEONTOLOGY. 

brian  Trilobites  very  commonly  have  either  a  great  many  rings 
(as  in  Paradox  ides,  fig.  31,  a),  or  else  very  few  (as  in  Agnostus, 
fig.  3 !,£•).  In  some  instances,  the  body-rings  do  not  seem  to 
have  been  so  constructed  as  to  allow  of  much  movement,  but 
in  other  cases  this  region  of  the  body  is  so  flexible  that  the 
animal  possessed  the  power  of  rolling  itself  up  completely,  like 
a  hedgehog  ;  and  many  individuals  have  been  permanently 
preserved  as  fossils  in  this  defensive  condition.  Finally,  the 
body  of  the  Trilobite  was  completed  by  a  tail-shield  (techni- 
cally termed  the  "  pygidium  "),  which  varies  much  in  size  and 
form,  and  is  composed  of  a  greater  or  less  number  of  rings, 
similar  to  those  which  form  the  thorax,  but  immovably  amalga- 
mated with  one  another  (fig.  31,  //). 

The  under  surface  of  the  body  in  the  Trilobites  appears  to 
have  been  more  or  less  entirely  destitute  of  hard  structures, 
with  the  exception  of  a  well-developed  upper  lip,  in  the  form 
of  a  plate  attached  to  the  inferior  side  of  the  head-shield  in 
front.  There  is  no  reason  to  doubt  that  the  animal  possessed 
legs;  but  these  structures  seem  to  have  resembled  'those  of 
many  living  Crustaceans  in  being  quite  soft  and  membranous. 
This,  at  any  rate,  seems  to  have  been  generally  the  case ; 
though  structures  which  have  been  regarded  as  legs  have  been 
detected  on  the  under  surface  of  one  of  the  larger  species  of 
Trilobites.  There  is  also,  at  present,  no  direct  evidence  that 
the  Trilobites  possessed  the  two  pairs  of  jointed  feelers  ("an- 
tennae") which  are  so  characteristic  of  recent  Crustaceans. 

The  Trilobites  vary  much  in  size,  and  the  Cambrian  forma- 
tion presents  examples  of  both  the  largest  and  the  smallest 
members  of  the  order.  Some  of  the  young  forms  may  be  little 
bigger  than  a  millet-seed,  and  some  adult  examples  of  the 
smaller  species  (such  as  Agnostus}  may  be  only  a  few  lines  in 
length  ;  whilst  such  giants  of  the  order  as  Paradoxides  and 
Asaphus  may  reach  a  length  of  from  one  to  two  feet.  Judging 
from  what  we  actually  know  as  to  the  structure  of  the  Trilo- 
bites, and  also  from  analogous  recent  forms,  it  would  seem  that 
these  ancient  Crustaceans  were  mud-haunting  creatures,  deni- 
zens of  shallow  seas,  and  affecting  the  soft  silt  of  the  bottom 
rather  than  the  clear  water  above.  Whenever  muddy  sedi- 
ments are  found  in  the  Cambrian  and  Silurian  formations, 
there  we  are  tolerably  sure  to  find  Trilobites,  though  they  are 
by  no  means  absolutely  wanting  in  limestones.  They  appear 
to  have  crawled  about  upon  the  sea-bottom,  or  burrowed  in  the 
yielding  mud,  with  the  soft  under  surface  directed  downwards; 
and  it  is  probable  that  they  really  derived  their  nutriment  from 
the  organic  matter  contained  in  the  ooze  amongst  which  they 


THE  CAMBRIAN    PERIOD.  87 

lived.  The  vital  organs  seem  to  have  occupied  the  central  lobe 
of  the  skeleton,  by  which  they  were  protected ;  and  a  series  of 
delicate  leaf-like  paddles,  which  probably  served  as  respiratory 
organs,  would  appear  to  have  been  carried  on  the  under  surface 
of  the  thorax.  That  they  had  their  enemies  may  be  regarded 
as  certain ;  but  we  have  no  evidence  that  they  were  furnished 
with  any  offensive  weapons,  or,  indeed,  with  any  means  of 
defence  beyond  their  hard  crust,  and  the  power,  possessed  by 
so  many  of  them,  of  rolling  themselves  into  a  ball.  An  addi- 
tional proof  of  the  fact  that  they  for  the  most  part  crawled 
along  the  sea-bottom  is  found  in  the  occurrence  of  tracks  and 
markings  of  various  kinds,  which  can  hardly  be  ascribed  to 
any  other  creatures  with  any  show  of  probability.  That  this 
is  the  true  nature  of  some  of  the  markings  in  question  cannot 
be  doubted  at  all ;  and  in  other  cases  no  explanation  so  pro- 
bable has  yet  been  suggested.  If,  however,  the  tracks  which 
have  been  described  from  the  Potsdam  Sandstone  of  North 
America  under  the  name  of  Protichnites  are  really  due  to  the 
peregrinations  of  some  Trilobite,  they  must  have  been  pro- 
duced by  one  of  the  largest  examples  of  the  order. 

As  already  said,  the  Cambrian  Rocks  are  very  rich  in  the 
remains  of  Trilobites.  In  the  lowest  beds  of  the  series  (Long- 
mynd  Rocks),  representatives  of  some  half-dozen  genera  have 
now  been  detected,  including  the  dwarf  Agnostus  and  the  giant 
Paradoxides.  In  the  higher  beds,  the  number  both  of  genera 
and  species  is  largely  increased ;  and  from  the  great  compara- 
tive abundance  of  individuals,  the  Trilobites  have  every  right 
to  be  considered  as  the  most  characteristic  fossils  of  the  Cam- 
brian period, — the  more  so  as  the  Cambrian  species  belong  to 
peculiar  types,  which,  for  the  most  part,  died  out  before  the 
commencement  of  the  Silurian  epoch. 

All  the  remaining  Cambrian  fossils  which  demand  any  notice 
here  are  members  of  one  or  other  division  of  the  great  class 
of  the  Mollusca,  or  "  Shell-fish  "  properly  so  called.  In  the 
Lower  Cambrian  Rocks  the  Lamp-shells  (Brachiopoda)  are  the 
principal  or  sole  representatives  of  the  class,  and  appear  chiefly 
in  three  interesting  and  important  types — namely,  Lingulella, 
Discina,  and  Obolella.  Of  these  the  last  (fig.  32,  /)  is  highly 
characteristic  of  these  ancient  deposits ;  whilst  Discina  is  one 
of  those  remarkable  persistent  types  which,  commencing  at 
this  early  period,  has  continued  to  be  represented  by  varying 
forms  through  all  the  intervening  geological  formations  up  to 
the  present  day.  Lingulella  (fig.  32,  c)9  again,  is  closely  allied 
to  the  existing  "  Goose-bill  "  Lamp-shell  (Lingula  anatina],  and 
thus  presents  us  with  another  example  of  an  extremely  long- 


88 


HISTORICAL   PALEONTOLOGY. 


lived  type.  The  Lingulellce  and  their  successors,  the  Litigufa, 
are  singular  in  possessing  a  shell  which  is  of  a  horny  texture, 
and  contains  but  a  small  proportion  of  calcareous  matter.  In 
the  Upper  Cambrian  Rocks,  the  Lingiilelltz  become  much  more 
abundant,  the  broad  satchel  -  shaped  species  known  as  Z. 
Davisii  (fig.  32,  e)  being  so  abundant  that  one  of  the  great 
divisions  of  the  Cambrian  is  termed  the  "Lingula  Flags." 
Here,  also,  we  meet  for  the  first  time  with  examples  of  the 
genus  Orthis  (fig.  32,  f,  k,  /)  a  characteristic  Palaeozoic  type  of 


Fig.  32. — Cambrian  Fossils  :  a,  Protospongiafenestrata,  Menevian  Group;  b,  Arettt- 
colitesdidymus,  Longmynd  Group;  c,  LinguleUafermginea,  Longmynd  and  Menevian, 
enlarged;  d,  Hymenocaris  vermicauda,  Lingula  Flags;  e,  Lingulella  Davisii,  Lingula 
Flags;/,  Orthis  lenticularis,  Lingula  Flags;  g,  Theca  Davidii,  Tremadoc  Slates;  h, 
Modiolopsis  Solvensts,  Tremadoc  Slates ;  i,  Obolella  sagittalis,  interior  of  valve,  Mene- 
vian ;  /,  Exterior  of  the  same  ;  k,  Orthis  Hicksii,  Menevian  ;  /,  Cast  of  the  same  ;  m, 
Olenus  micrurus,  Lingula  Flags.  (Alter  Salter,  Hicks,  and  Davidson.) 

the  Brachiopods,  which  is  destined  to  undergo  a  vast  extension 
in  later  ages. 

Of  the  higher  groups  of  the  Molhisca  the  record  is  as  yet 
but  scanty.  In  the  Lower  Cambrian,  we  have  but  the  thin, 
fragile,  dagger  -  shaped  shells  of  the  free  -  swimming  oceanic 
Molluscs  or  "  Winged-snails  "  (Ptervpoda),  of  which  the  most 
characteristic  is  the  genus  Theca  (fig.  32,  g).  In  the  Upper 
Cambrian,  in  addition  to  these,  we  have  a  few  Univalves 
(Gasteropoda],  and,  thanks  to  the  researches  of  Dr  Hicks, 
quite  a  small  assemblage  of  Bivalves  (Lamellibranchiata) , 
though  these  are  mostly  of  no  great  dimensions  (fig.  32,  h). 
Of  the  chambered  Cephalopoda  (Cuttle-fishes  and  their  allies), 


THE  CAMBRIAN   PERIOD. 


89 


we  have  but  few  traces,  and  these  wholly  confined  to  the  higher 

beds  of  the  formation.     We  meet,  however,  with  examples  of 

the  wonderful   genus  Orthoceras,  with    its 

straight,  partitioned  shell,  which  we  shall 

find  in  an  immense  variety  of  forms  in  the 

Silurian    rocks.      Lastly,   it  is  worthy  of 

note  that  the  lowest  of  all  the  groups  of 

the  Mollusca  —  namely,  that  of  the   Sea- 

mats,  Sea-mosses,  and  Lace-corals  (Po!y- 

zod] — is  only  doubtfully  known    to  have 

any    representatives    in     the     Cambrian, 

though   undergoing   a    large    and    varied 

development  in  the  Silurian  deposits. 

An  exception,  however,  may  with  much 
probability  be  made  to  this  statement  in 
favour  of  the  singular  genus  Dictyonema 
(fig.  33),  which  is  highly  characteristic  of 
the  highest  Cambrian  beds  (Tremadoc 
Slates).  This  curious  fossil  occurs  in  the 
form  of  fan-like  or  funnel-shaped  expan- 
sions, composed  of  slightly-diverging  horny  branches,  which 
are  united  in  a  net-like  manner  by  numerous  delicate  cross- 
bars, and  exhibit  a  row  of  little  cups  or  cells,  in  which  the  ani- 
mals were  contained,  on  each  side.  Dictyonema  has  generally 
been  referred  to  the  Graptolites ;  but  it  has  a  much  greater 
affinity  with  the  plant-like  Sea-firs  (Sertularians]  or  the  Sea- 
mosses  (Polyzoa),  and  the  balance  of  evidence  is  perhaps  in 
favour  of  placing  it  with  the  latter. 


Fig.  33.  — Fragment  of 
Dictyonema  sociale,  con- 
siderably enlarged,  show- 
ing the  horny  branches, 
with  their  connecting 
cross-bars,  and  with  a  row 
of  cells  on  each  side. 
(Original.) 


'LITERATURE. 

The  following  are  the  more  important  and  accessible  works  and  memoirs 
which  may  be  consulted  in  studying  the  stratigraphical  and  paloeontolo- 
gical  relations  of  the  Cambrian  Rocks  : — 

(1)  'Siluria.'     Sir  Roderick  Murchison.     5th  ed.,  pp.  21-46. 

(2)  'Synopsis   of   the  Classification  of  the  British   Palaeozoic  Rocks.' 

Sedgwick.  Introduction  to  the  3d  Fasciculus  of  the  'Descrip- 
tions of  British  Palaeozoic  Fossils  in  the  Woodwardian  Museum,' 
by  F.  M'Coy,  pp.  i-xcviii,  1855. 

(3)  '  Catalogue  of  the  Cambrian  and  Silurian  Fossils  in  the  Geological 

Museum  of -the  University  of  Cambridge.'  Salter.  With  a  Pref- 
ace by  Prof.  Sedgwick.  1873. 

(4)  'Thesaurus  Siluricus.'     Bigsby.      1868. 

(5)  "  History  of  the  Names  Cambrian  and  Silurian."     Sterry  Hunt. — 

'  Geological  Magazine. '     1873. 

(6)  '  Systeme  Silurien  du  Centre  de  la  Boheme.'     Barrande.     Vol.  I. 

(7)  '  Report  of  Progress  of  the  Geological  Survey  of  Canada,  from  its 

Commencement  to  1863,'  pp.  87-109. 


90  HISTORICAL   PALEONTOLOGY. 

(8)  'Acadian  Geology.'     Dawson.     Pp.  641-657. 

(9)  "Guide  to  the  Geology  of  New  York,"  Lincklaen  ;  and  "Contribu- 

tions to  the  Palaeontology  of  New  York,"  James  Hall.  — '  Four- 
teenth Report  on  the  State  Cabinet.'     1 86 1. 

(10)  '  Pafteozoic  Fossils  of  Canada.'     Billings.      1865. 

(11)  '  Manual  of  Geology.'     Dana.     Pp.  166-182.     2d  ed.      1875. 

(12)  "Geology   of  North  Wales,"    Ramsay;    with    Appendix   on   the 

Fossils,   Salter. — 'Memoirs   of  the  Geological  Survey  of  Great 
Britain,'  vol.  iii.      1866. 

(13)  "  On  the  Ancient  Rocks  of  the  St  David's  Promontory,  South  Wales, 

•   and  their   Fossil   Contents."      Harkness   and    Hicks. — 'Quart. 
Journ.  Geol.  Soc.,'  xxvii.  384-402.      1871. 

(14)  "On  the  Tremadoc  Rocks  in  the  Neighbourhood   of  St  David's, 

South   Wales,    and   their  Fossil   Contents."      Hicks.  —  'Qurrt. 
Journ.  Geol.  Soc.,'  xxix.  39-52.      1873. 

In  the  above  list,  allusion  has  necessarily  been  omitted  to  numerous 
works  and  memoirs  on  the  Cambrian  deposits  of  Sweden  and  Norway, 
Central  Europe,  Russia,  Spain,  and  various  parts  of  North  America,  as 
well  as  to  a  number  of  important  papers  on  the  British  Cambrian  strata  by 
various  well-known  observers.  Amongst  these  latter  may  be  mentioned 
memoirs  by  Prof.  Phillips,  and  Messrs  Salter,  Hicks,  Belt,  Plant,  Hom- 
fray,  Ash,  Holl,  &c. 


CHAPTER     IX. 
THE  LOWER  SILURIAN  PERIOD. 

The  great  system  of  deposits  to  which  Sir  Roderick  Murchi- 
son  applied  the  name  of  "  Silurian  Rocks  "  reposes  directly 
upon  the  highest  Cambrian  beds,  apparently  without  any 
marked  unconformity,  though  with  a  considerable  change  in 
the  nature  of  the  fossils.  The  name  "  Silurian  "  was  originally 
proposed  by  the  eminent  geologist  just  alluded  to  for  a  great 
series  of  strata  lying  below  the  Old  Red  Sandstone,  and  occu- 
pying districts  in  Wales  and  its  borders  which  were  at  one 
time  inhabited  by  the  "Silures,"  a  tribe  of  ancient  Britons. 
Deposits  of  a  corresponding  age  are  row  known  to  be  largely 
developed  in  other  parts  of  England,  in  Scotland,  and  in  Ire- 
land, in  North  America,  in  Australia,  in  India,  in  Bohemia, 
Saxony,  Bavaria,  Russia,  Sweden  and  Norway,  Spain,  and  in 
various  other  regions  of  less  note.  In  some  regions,  as  in  the 
neighbourhood  of  St  Petersburg,  the  Silurian  strata  are  found 
not  only  to  have  preserved  their  original  horizontality,  but  also 
to  have  retained  almost  unaltered  their  primitive  soft  and  inco- 
herent nature.  In  other  regions,  as  in  Scandinavia  and  many 


THE   LOWER   SILURIAN    PERIOD.  91 

parts  of  North  America,  similar  strata,  now  consolidated  into 
shales,  sandstones,  and  limestones,  may  be  found  resting  with 
a  very  slight  inclination  on  still  older  sediments.  In  a  great 
many  regions,  however,  the  Silurian  deposits  are  found  to  have 
undergone  more  or  less  folding,  crumpling,  and  dislocation, 
accompanied  by  induration  and  " cleavage"  of  the  finer  and 
softer  sediments  ;  whilst  in  some  regions,  as  In  the  Highlands 
of  Scotland,  actual  "  metamorphism "  has  taken  place.  In 
consequence  of  the  above,  Silurian  districts  usually  present 
the  bold,  rugged,  and  picturesque  outlines  which  are  char- 
acteristic of  the  older  "Primitive"  Tocks  of  the  earth's  crust  in 
general.  In  many  instances,  we  find  Silurian  strata  rising  into 
mountain-chains  of  great  grandeur  and  sublimity,  exhibiting 
the  utmost  diversity  of  which  rock-scenery  is  capable,  and  de- 
lighting the  artist  with  endless  changes  of  valley,  lake,  and 
cliff.  Such  districts  are  little  suitable  for  agriculture,  though  this 
is  often  compensated  for  by  the  valuable  mineral  products  con- 
tained in  the  rocks.  On  the  other  hand,  when  the  rocks  are 
tolerably  soft  and  uniform  in  their  nature,  or  when  few  disturb- 
ances of  the  crust  of  the  earth  have  taken  place,  we  may  find 
Silurian  areas  to  be  covered  with  an  abundant  pasturage  or  to 
be  heavily  timbered. 

Under  the  head  of  "  Silurian  Rocks,"  Sir  Roderick  Murchi- 
son  included  all  the  strata  between  the  summit  of  the  "  Long- 
mynd"  beds  and  the  Old  Red  Sandstone,  and  he  divided  these 
into  the  two  great  groups  of  the  Lower  Silurian  and  Upper  Silu- 
rian. It  is,  however,  now  generally  admitted  that  a  considerable 
portion  of  the  basement  beds  of  Murchison's  Silurian  series 
must  be  transferred — if  only  upon  palseontological  grounds — to 
the  Upper  Cambrian,  as  has  here  been  done;  and  much  contro- 
versy has  been  carried  on  as  to  the  proper  nomenclature  of  the 
Upper  Silurian  and  of  the  remaining  portion  of  Murchison's 
Lower  Silurian.  Thus,  some  would  confine  the  name  *'  Silu- 
rian "  exclusively  to  the  Upper  Silurian,  and  would  apply  the 
name  of  "  Cambro-Silurian  "  to  the  Lower  Silurian,  or  would 
include  all  beds  of  the  latter  age  in  the  "  Cambrian  "  series  of 
Sedgwick.  It  is  not  necessary  to  enter  into  the  merits  of  these 
conflicting  views.  For  our  present  purpose,  it  is  sufficient  to 
recognise  that  there  exist  two  great  groups  of  rocks  between 
the  highest  Cambrian  beds,  as  here  defined,  and  the  base  of 
the  Devonian  or  Old  Red  Sandstone.  These  two  great  groups 
are  so  closely  allied  to  one  another,  both  physically  and  palaa- 
ontologically,  that  many  authorities  have  established  a  third 
or  intermediate  group  (the  "  Middle  Silurian  "),  by  which  a  pas- 


92  HISTORICAL   PALEONTOLOGY. 

sage  is  made  from  one  into  the  other.  This  method  of  pro- 
cedure involves  disadvantages  which  appear  to  outweigh  its 
advantages ;  and  the  two  groups  in  question  are  not  only  gen- 
erally capable  of  very  distinct  stratigraphical  separation,  but  at 
the  same  time  exhibit,  together  with  the  alliances  above  spoken 
of,  so  many  and  such  important  palaeontological  differences, 
that  it  is  best  to  consider  them  separately.  We  shall  there- 
fore follow  this  course  in  the  present  instance ;  and  pending 
the  final  solution  of  the  controversy  as  to  Cambrian  and  Silu- 
rian nomenclature,  we  shall  distinguish  these  two  groups  of 
strata  as  the  "  Lower  Silurian"  and  the  u  Upper  Silurian." 

The  Lower  Silurian  Rocks  are  known  already  to  be  devel- 
oped in  various  regions;  and  though  \\~\z\\  general  succession 
in  these  areas  is  approximately  the  same,  each  area  exhibits 
peculiarities  of  its  own,  whilst  the  subdivisions  of  each  are 
known  by  special  names.  All,  therefore,  that  can  be  attempted 
here,  is  to  select  two  typical  areas — such  as  Wales  and  North 
America — and  to  briefly  consider  the  grouping  and  divisions 
of  the  Lower  Silurian  in  each. 

In  Wales,  the  line  between  the  Cambrian  and  Lower  Silurian 
is  somewhat  ill-defined,  and  is  certainly  not  marked  by  any 
strong  unconformity.  There  are,  however,  grounds  for  accept- 
ing the  line  proposed,  for  palseontological  reasons,  by  Dr 
Hicks,  in  accordance  with  which  the  Tremadoc  Slates  ("Lower 
Tremadoc"  of  Salter)  become  the  highest  of  the  Cambrian 
deposits  of  Britain.  If  we  take  this  view,  the  Lower  Silurian 
rocks  of  Wales  and  adjoining  districts  are  found  to  have  the 
following  general  succession  from  below  upwards  (fig.  34) : — - 

1.  The  Arenig  Group. — This  group  derives  its  name  from 
the  Arenig  mountains,  where  it  is  extensively  developed.     It 
consists  of  about  4000  feet  of  slates,  shales,  and  flags,  and  is 
divisible  into  a  lower,  middle,  and  upper  division,  of  which  the 
firmer  is  often  regarded  as   Cambrian   under  the   name   of 
'•  Upper  Tremadoc  Slates." 

2.  The  Llandeilo  Group. — The  thickness  of  this  group  varies 
from  about  4000  to  as  much  as  10,000  feet;  but  in  this  latter 
case  a  great  amount  of  the  thickness  is  made  up  of  volcanic 
ashes  and  interbedded  traps.     The  sedimentary  beds  of  this 
group  are  principally  slates  and  flags,  the  latter  occasionally 
with  calcareous  bands ;  and  the  whole  series  can  be  divided 
into  a  lower,  middle,  and  upper  Llandeilo  division,  of  which 
the  last  is  the  most  important.     The  name  of  "  Llandeilo"  is 
derived  from  the  town  of  the  same  name  in  Wales,  where  strata 
of  this  age  were  described  by  Murchison. 


THE   LOWER   SILURIAN    PERIOD.  93 

3.  The  Caradoc  or  Bala  Group. — The  alternative  names  of 
this  group  are  also  of  local  origin,  and  are  derived,  the  one 
from  Caer  Caradoc  in  Shropshire,  the  other  from  Bala  in  Wales, 
strata  of  this  age  occurring  in  both  localities.     The  series  is 
divided  into  a  lower  and  upper  group,  the  latter  chiefly  com- 
posed of  shales  and  flags,  and  the  former  of  sandstones  and 
shales,  together  with  the  important  and  interesting  calcareous 
band  known  as  the  "  Bala  Limestone.''     The  thickness  of  the 
entire  series  varies  from  4000  to  as  much  as  12,000  feet,  ac- 
cording as  it  contains  more  or  less  of  interstratified  igneous 
rocks. 

4.  The  Llandovery  Group  (Lower  Llandovery  of  Murchison). 
— This  series,  as  developed  near  the  town  of  Llandovery,  in 
Caermarthenshire,  consists  of  less  than  1000  feet  of  conglom- 
erates, sandstones,  and  shales.     It  is  probable,  however,  that 
the  little  calcareous  band  known  as  the  "  Hirnant  Limestone," 
together  with  certain  pale-coloured  slates  which  lie  above  the 
Bala  Limestone,  though  usually  referred  to  the  Caradoc  series, 
should  in  reality  be  regarded  as  belonging  to  the  Llandovery 
group. 

The  general  succession  of  the  Lower  Silurian  strata  of  Wales 
and  its  borders,  attaining  a  maximum  thickness  (along  with 
contemporaneous  igneous  matter)  of  nearly  30,000  feet,  is 
diagramatically  represented  in  the  annexed  sketch-section 
(fig.  34) :— . 


[GENERALISED  SECTION 


94 


HISTORICAL  PALAEONTOLOGY. 


GENERALISED  SECTION  OF  THE  LOWER  SILURIAN  ROCKS 
OF  WALES. 


Fig.  34- 


(  May  Hill  Sandstone  (base 
|      of  Upper  Silurian). 

Llandovery  Group. 


Upper  Bala. 

Lower  Bala. 

Upper  Llandeilo. 
Middle  Llandeilo. 
Lower  Llandeilo. 

Upper  Arenig. 
Middle  Arenig. 


Lower      Arenig     (Upper 
Tremadoc  Group). 

j  Tremadoc   Slates  (Lower 
|      Tremadoc  Group). 


In  North  America,  both  in  the  United  States  and  in  Can- 
ada, the  Silurian  rocks  are  very  largely  developed,  and  may  be 


THE   LOWER    SILURIAN    PERIOD.  95 

regarded  as  constituting  an  exceedingly  full  and  typical  series 
of  the  deposits  of  this  period.  The  chief  groups  of  the  Silurian 
rocks  of  North  America  are  as  follows,  beginning,  as  before, 
with  the  lowest  strata,  and  proceeding  upwards  (fig.  35) : — 

1.  Quebec  Group. — This  group  is  typically  developed   in 
the  vicinity  of  Quebec,  where  it  consists  of  about  5000  feet  of 
strata,  chiefly  variously  -  coloured  shales,  together  with  some 
sandstones  and  a  few  calcareous  bands.     It  contains  a  number 
of  peculiar  Graptolites,  by  which  it  can  be  identified  without 
question  with  the  Arenig  group  of  Wales  and  the  correspond- 
ing Skiddaw  Slates  of  the  North  of  England.     It  is  also  to  be 
noted  that  numerous  Trilobites  of  a  distinct  Cambrian  fades 
have  been  obtained  in  the  limestones  of  the  Quebec  group, 
near  Quebec.     These  fossils,  however,  have  been  exclusively 
obtained  from  the  limestones  of  the  group ;  and  as  these  lime- 
stones are  principally  calcareous  breccias  or  conglomerates, 
there  is  room  for  believing  that  these  primordial  fossils  are 
really  derived,  in  part  at  any  rate,  from  fragments  of  an  upper 
Cambrian  limestone.     In  the  State  of  New  York,  the  Grapto- 
litic  shales  of  Quebec  are  wanting ;  and  the  base  of  the  Silurian 
is  constituted  by  the  so-called  "  Calciferous  Sand-rock"  and 
"  Chazy  Limestone."*     The  first  of  these  is  essentially  and 
typically  calcareous,  and  the  second  is  a  genuine  limestone. 

2.  The  Trenton  Group. — This  is  an  essentially  calcareous 
group,  the  various  limestones  of  which  it  is  composed  being 
known  as  the  "  Bird's-eye,"  "  Black  River,"  and  "  Trenton  " 
Limestones,  of  which  the  last  is  the  thickest  and  most  import- 
ant.    The  thickness  of  this  group  is  variable,  and  the  bands  of 
limestone  in  it  are  often  separated  by  beds  of  shale. 

3.  The   Cincinnati  Group  (Hudson  River  Formation t). — 
This  group  consists  essentially  of  a  lower  series  of  shales,  often 
black  in   colour  and  highly  charged  with  bituminous  matter 
(the  "  Utica  Slates  "),  and  of  an  upper  series  of  shales,  sand- 

*  The  precise  relations  of  the  Quebec  shales  with  Graptolites  (Levis 
Formation)  to  the  Calciferous  and  Chazy  beds  are  still  obscure,  though 
there  seems  little  doubt  but  that  the  Quebec  Shales  are  superior  to  the 
Calciferous  Sand-rock. 

t  There  is  some  difficulty  about  the  precise  nomenclature  of  this  group. 
It  was  originally  called  the  "Hudson  River  Formation;  "  but  this  name 
is  inappropriate,  as  rocks  of  this  age  hardly  touch  anywhere  the  actual 
Hudson  River  itself,  the  rocks  so  called  formerly  being  now  known  to  be 
of  more  ancient  date.  There  is  also  some  want  of  propriety  in  the  name  of 
"  Cincinnati  Group,"  since  the  rocks  which  are  known  under  this  name  in 
the  vicinity  of  Cincinnati  itself  are  the  representatives  of  the  Trenton 
Limestone,  Utica  Slates,  and  the  old  Hudson  River  group,  inseparably 
united  in  what  used  to  be  called  the  "  IMu-  Limestone  Series." 


96 


HISTORICAL    PALEONTOLOGY. 


stones,  and  limestones  (the  "  Cincinnati "  rocks  proper).  The 
exact  parallelism  of  the  Trenton  and  Cincinnati  groups  with 
the  subdivisions  of  the  Welsh  Silurian  series  can  hardly  be 
stated  positively.  Probably  no  precise  equivalency  exists ; 
but  there  can  be  no  doubt  but  that  the  Trenton  and  Cincin- 
nati groups  correspond,  as  a  whole,  with  the  Llandeilo  and 
Caradoc  groups  of  Britain.  The  subjoined  diagrammatic 
section  (fig.  35)  gives  a  general  idea  of  the  succession  of  the 
Lower  Silurian  rocks  of  North  America  : — 

GENERALISED  SECTION  OF  THE  LOWER  SILURIAN  ROCKS 
OF  NORTH  AMERICA. 

Fig.  35- 


Medina      Sandstone     (base     of 
Upper  Silurian). 


Cincinnati  Group  proper. 


Utica  Slates. 

Ticnton  Limestone. 

Black  River  Limestone. 

Bird's-eye  Limestone. 

-Chazy  Limestone. 

Quebec  Shales  (Levis  Beds). 

Calciftrous  Sand-reck. 
Potsdam  Sandstone. 


THE    LOWER    SILURIAN    PERIOD. 


97 


Of  the  life  of  the  Lower  Silurian  period  we  have  record  in  a 
vast  number  of  fossils,  showing  that  the  seas  of  this  period 
were  abundantly  furnished  with  living  denizens.  We  rte!ve,c 
however,  in  the  meanwhile,  no  knowledge  of  the  land-surffeces" 
of  the  period.  We  have  therefore  no  means  of  speculaitlng 
as  to  the  nature  of  the  terrestrial  animals  of  this  ancient  -age,T 
nor  is  anything  known  with  certainty  of  any  land-plants  which 
may  have  existed.  The  only  relics  of  vegetation  upon  which 
a  positive  opinion  can  be  expressed  belong  to  the  obscure 
group  of  the  "  Fucoids,"  and  are  supposed  to  be  the  remains 
of  sea-weeds.  Some  of  the  fossils  usually  placed  under  this 
head  are  probably  not  of  a  vegetable  nature  at  all,  but  others 


Fig.  36.—  Licrophycus  Ottaivaensis,  a  "  Fucoid,"  from  the  Trenton  Limestone 
^Lower  Silurian)  of  Canada.     (After  Billings.) 

(fig.  36)  appear  to  be  unquestionable  plants.  The  true  affin- 
ities of  these,  however,  are  extremely  dubious.  All  that  can 
be  said  is,  that  remains  which  appear  to  be  certainly  vegetable, 


98 


HISTORICAL   PALEONTOLOGY. 


and  which  are  most  probably  due  to  marine  plants,  have  been 
recognised  nearly  at  the  base  of  the  Lower  Silurian  (Arenig), 
and  that  they  are  found  throughout  the  series  whenever  suitable 
conditions  recur. 

The  Protozoans  appear  to  have  flourished  extensively  in  the 
Lower  Silurian  seas,  though  to  a  large  extent  under  forms 
which  are  still  little  understood.  We  have  here  for  the  first 
time  the  appearance  of  Foraminifera  of  the  ordinary  type — one 
of  the  most  interesting  observations  in  this  connection  being 
that  made  by  Ehrenberg,  who  showed  that  the  Lower  Silurian 
sandstones  of  the  neighbourhood  of  St  Petersburg  contained 
casts  in  glauconite  of  Foraminiferous  shells,  some  of  which  aie 
referable  to  the  existing  genera  Rotalia  and  Textularia.  True 
Sponges,  belonging  to  that  section  of  the  group  in  which  the 
skeleton  is  calcareous,  are  also  not  unknown,  one  of  the  most 

characteristic  genera  being  As- 
tylospongia  (fig.  37).  In  this 
genus  are  included  more  or  less 
globular,  often  lobed  sponges, 
which  are  believed  not  to  have 
been  attached  to  foreign  bodies. 
In  the  form  here  figured  there 
is  a  funnel-shaped  cavity  at  the 
summit;  and  the  entire  mass  of 
the  sponge  is  perforated,  as  in 
living  examples,  by  a  system 
of  canals  which  convey  the 
sea-water  to  all  parts  of  the 
organism.  The  canals  by 
which  the  sea-water  gains  en- 
trance open  on  the  exterior  of 
the  sphere,  and  those  by  which 
it  again  escapes  from  the  sponge  open  into  the  cup-shaped 
depression  at  the  summit. 

The  most  abundant,  and  at  the  same  time  the  least  under- 
stood, of  Lower  Silurian  Protozoans  belong,  however,  to  the 
genera  Stromatopora  and  Receptaculites,  the  structure  of  which 
can  merely  be  alluded  to  here.  The  specimens  of  Stromato- 
pora (fig.  38)  occur  as  hemispherical,  pear-shaped,  globular,  or 
irregular  masses,  often  of  very  considerable  size,  and  some- 
times demonstrably  attached  to  foreign  bodies.  In  their  struc- 
ture these  masses  consist  of  numerous  thin  calcareous  laminae, 
usually  arranged  concentrically,  and  separated  by  narrow 
interspaces.  These  interspaces  are  generally  crossed  by 
numerous  vertical  calcareous  pillars,  giving  the  vertical  sectioa 


cetiiorsa*  cut 


Fig.  37.  —Astylospongia  fi 
vertically  so  as  to  exhibit  the  canal-system 
in  the  interior.  Lower  Silurian,  Tennessee. 
(After  Ferdinand  Rosmer.) 


THE    LOWER    SILURIAN    PERIOD.  99 

of  the  fossil  a  lattice-like  appearance.     There  are  also  usually 
minute  pores  in  the  concentric  laminae,  by  which  the  successive 


Fig.  38. — A  small  and  perfect  specimen  of  S tromaeopora  rugosa,  of  the  natural 
size,  from  the  Trenton  Limestone  of  Canada.     (After  Billings.) 

interspaces  are  placed  in  communication ;  and  sometimes  the 
surface  presents  large  rounded  openings,  which  appear  to  corre- 
spond with  the  water-canals  of  the  Sponges.  Upon  the  whole, 
though  presenting  some  curious  affinities  to  the  calcareous 
Sponges,  Stromatopora  is  perhaps  more  properly  regarded  as 
a  gigantic  Foraminifer.  If  this  view  be  correct,  it  is  of  special 
interest  as  being  probably  the  nearest  ally  of  Eozoon,  the 
general  appearance  of  the  two  being  strikingly  similar,  though 
their  minute  structure  is  not  at  all  the  same.  Lastly,  in  the 
fossils  known  as  Receptaculites  and  Ischadites  we  are  also  pre- 
sented with  certain  singular  Lower  Silurian  Protozoans,  which 
may  with  great  probability  be  regarded  as  gigantic  Forami- 
nifera.  Their  structure  is  very  complex;  but  fragments  are 
easily  recognised  by  the  fact  that  the  exterior  is  covered  with 
numerous  rhomboidal  calcareous  plates,  closely  fitting  together, 
and  arranged  in  peculiar  intersecting  curves,  presenting  very 
much  the  appearance  of  the  engine-turned  case  of  a  watch. 

Passing  next  to  the  sub-kingdom  of  Cc&lenterate  animals 
(Zoophytes,  Corals,  &c.),  we  find  that  this  great  group,  almost 
or  wholly  absent  in  the  Cambrian,  is  represented  in  Lower 


100  HISTORICAL   PALEONTOLOGY. 

Silurian  deposits  by  a  great  number  of  forms  belonging  on  the 
one  hand  to  the  true  Corals,  and  on  the  other  hand  to  tine 
singular  family  of  the  Graptolites.  If  we  except  certain  plant- 
like  fossils  which  probably  belong  rather  to  the  Sertularians 
or  the  Polyzoans  (e.  g.,  Dictyonema,  Dendrograptus,  £c.),  the 
family  of  the  Graptolites  may  be  regarded  as  exclusively 
Silurian  in  its  distribution.  Not  only  is  this  the  case,  but  it 
attained  its  maximum  development  almost  upon  its  first  ap- 
pearance, in  the  Arenig  Rocks;  and  whilst  represented  by  a 
great  variety  of  types  in  the  Lower  Silurian,  it  only  exists  in 
the  Upper  Silurian  in  a  much  diminished  form.  '^\\z  Grap- 
tolites (Gr.  grap/w,  I  write ;  lithos,  stone)  were  so  named  by 
Linnaeus,  from  the  resemblance  of  some  of  them  to  written  or 
pencilled  marks  upon  the  stone,  though  the  great  naturalist  him- 
self did  not  believe  them  to  be  true  fossils  at  all.  They  occur 
as  linear  or  leaf-like  bodies,  sometimes  simple,  sometimes  com- 
pound and  branched ;  and  no  doubt  whatever  can  be  enter- 
tained as  to  their  being  the  skeletons  of  composite  organisms, 
or  colonies  of  semi-independent  animals  united  together  by 
a  common  fleshy  trunk,  similar  to  what  is  observed  in  the 
colonies  of  the  existing  Sea-firs  (Sertularians).  This  fleshy 
trunk  or  common  stem  of  the  colony  was  protected  by  a  deli- 
cate horny  sheath,  and  it  gave  origin  to  the  little  flower-like 
"  polypites,"  which  constituted  the  active  element  of  the  whole 
assemblage.  These  semi-independent  beings  were,  in  turn, 
protected  each  by  a  little  horny  cup  or  cell,  directly  connected 
with  the  common  sheath  below,  and  terminating  above  in  an 
opening  through  which  the  polypite  could  protrude  its  tentacled 
head  or  could  again  withdraw  itself  for  safety.  The  entire 
skeleton,  again,  was  usually,  if  not  universally,  supported  by 
a  delicate  horny  rod  or  "axis,"  which  appears  to  have  been 
hollow,  and  which  often  protrudes  to  a  greater  or  less  extent 
beyond  one  or  both  of  the  extremities  of  the  actual  colony. 

The  above  gives  the  elementary  constitution  of  any  Grapto- 
lite,  but  there  are  considerable  differences  as  to  the  manner  in 
which  these  elements  are  arranged  and  combined.  In  some 
forms  the  common  stem  of  the  colony  gives  origin  to  but  a 
single  row  of  cells  on  one  side.  If  the  common  stem  is  a 
simple,  straight,  or  slightly-curved  linear  body,  then  we  have 
the  simplest  form  of  Graptolite  known  (the  genus  Monograptus}\ 
and  it  is  worthy  of  note  that  these  simple  types  do  not  come 
into  existence  till  comparatively  late  (Llandeilo),  and  last 
nearly  to  the  very  close  of  the  Upper  Silurian.  In  other 
cases,  whilst  there  is  still  but  a  single  row  of  cells,  the  colony 
may  consist  of  two  of  these  simple  stems  springing  from  a 


THE   LOWER   SILURIAN    PERIOD. 


IOI 


common  point,  as  in  the  so-called  "  twin  Graptolites  "  (Didy- 
mograptus,  fig.  40).    This  type  is  entirely  confined  to  the  earlier 

portion  of  the  Lower  Silu- 
rian period  (Arenig  and 
Llandeilo).  In  other  cases, 
again,  there  may  be  four 
of  such  stems  springing 
from  a  central  point  ( Tct- 
ragraplus).  Lastly,  there 
are  numerous  complex 
forms  (such  as  Dichograp- 
tus,  Loganograptus,  &c.)  in 
which  there  are  eight  or 
more  of  these  simple  bran- 
ches, all  arising  from  a 
common  centre  (fig.  39), 
which  is  sometimes  fur- 
nished with  a  singular 
horny  disc.  These  com- 
plicated branching  forms, 
as  well  as  the  Tetragrapti, 
are  characteristic  of  the 
horizon  of  the  Arenig 
group.  Similar  forms,  of- 
ten specifically  identical, 


Fig.  39. — Dichografitus  octobrachiatus.  a  branched,  "  unicellular  "  Graptolite  from 
the  Skiddaw  and  Quebec  Groups  (Arenig).     (After  Hall.) 

are  found  at  this  horizon  in  Wales,  in  the  great  series  of  the 
Skiddaw  Slates  of  the  north  of  England,  in  the  Quebec  group 
in  Canada,  in  equivalent  beds  in  Sweden,  and  in  certain  gold- 
bearing  slates  of  the  same  age  in  Victoria  in  Australia. 

In  another  great  group  of  Graptolites  (including  the  genera 
Diplograptus,  Dicranograptus,  Climacograptus,  &c.)  the  common 
stem  of  the  colony  gives  origin,  over  part  or  the  whole  of  its 
length,  to  two  rows  of  cells,  one  on  each  side  (fig.  41).  These 
double-celled  "  Graptolites  are  highly  characteristic  of  the 
Lower  Silurian  deposits ;  and,  with  an  exception  more  appa- 


102 


HISTORICAL    PALAEONTOLOGY. 


rent  than   real  in  Bohemia,  they  are  exclusively  confined  to 
strata  of  Lower  Silurian  age,  and  are  not  known  to  occur  in 


Fig.  40.—  Central  portion  of  the  colony  of  Did)  wcgraptus  divaria 
Llandeilo,  Dumfriesshire.     (Original.) 

the  Upper  Silurian.     Lastly,  there  is  a  group  of  Graptolites 
$-,  fig.  42)  in  which  the  colony  is  leaf-like  in  form, 


Fig.  41. — Examples  of  Diplograptus 
pristis,  showing  variations  in  the  appen- 
dages at  the  base.  Upper  Llandeilo, 
Dumfriesshire.  (Original.) 


Fig.  42. — Group  of  individuals  of  Phyllo- 
graptns  typus,  from  the  Quebec  group  of 
Canada.  (After  Hall.)  One  of  the  four  rows 
of  cells  is  hidden  on  the  under  surface. 


and  is  composed  of  four  rows  of  cells  springing  in  a  cross-like 


THE    LOWER   SILURIAN    PERIOD.  103 

manner  from  the  common  stem.    These  forms  are  highly  char- 
acteristic of  the  Arenig  group. 

The  Graptolites  are  usually  found  in  dark-coloured,  often 
black  shales,  which  sometimes  contain  so  much  carbon  as  to 
become  "  anthracitic."  They  may  be  simply  carbonaceous ; 
but  they  are  more  commonly  converted  into  iron-pyrites,  when 
they  glitter  with  the  brilliant  lustre  of  silver  as  they  lie  scattered 
on  the  surface  of  the  rock,  fully  deserving  in  their  metallic 
tracery  the  name  of  "written  stones."  They  constitute  one 
of  the  most  important  groups  of  Silurian  fossils,  and  are  of  the 
greatest  value  in  determining  the  precise  stratigraphical  posi- 
tion of  the  beds  in  which  they  occur.  They  present,  however, 
special  difficulties  in  their  study  ;  and  it  is  still  a  moot  point  as 
to  their  precise  position  in  the  zoological  scale.  The  balance 
of  evidence  is  in  favour  of  regarding  them  as  an  ancient  and 
peculiar  group  of  the  Sea-firs  (Hydroid  Zoophytes),  but  some 
regard  them  as  belonging  rather  to  the  Sea-mosses  (Poly zoo], 
Under  any  circumstances,  they  cannot  be  directly  compared 
either  with  the  ordinary  Sea-firs  or  the  ordinary  Sea-mosses  ; 
for  these  two  groups  consist  of  fixed  organisms,  whereas  the 
Graptolites  were  certainly  free-floating  creatures,  living  at 
large  in  the  open  sea.  The  only  Hydroid  Zoophytes  or  Poly- 
zoans  which  have  a  similar  free  mode  of  existence,  have  either 
no  skeleton  at  all,  or  have  hard  structures  quite  unlike  the 
horny  sheaths  of  the  Graptolites. 

The  second  great  group  of  Ccelenterate  animals  (Actinozoa} 
is  represented  in  the  Lower  Silurian  rocks  by  numerous 
Corals.  These,  for  obvious  reasons,  are  much  more  abundant 
in  regions  where  the  Lower  Silurian  series  is  largely  calcareous 
(as  in  North  America)  than  in  districts  like  Wales,  where 
limestones  are  very  feebly  developed.  The  Lower  Silurian 
Corals,  though  the  first  of  their  class,  and  presenting  certain 
peculiarities,  may  be  regarded  as  essentially  similar  in  nature 
to  existing  Corals.  These,  as  is  well  known,  are  the  calcareous 
skeletons  of  animals  —  the  so-called  "  Coral  -  Zoophytes  "- 
closely  allied  to  the  common  Sea-anemones  in  structure  and 
habit.  A  simple  coral  (fig.  43)  consists  of  a  calcareous  cup 
embedded  in  the  soft  tissues  of  the  flower-like  polype,  and  hav- 
ing at  its  summit  a  more  or  less  deep  depression  (the  "  calice  ") 
in  which  the  digestive  organs  are  contained.  The  space  within 
the  coral  is  divided  into  compartments  by  numerous  vertical 
calcareous  plates  (the  "  septa  "),  which  spring  from  the  inside 
of  the  wall  of  the  cup,  and  of  which  some  generally  reach  the 
centre.  Compound  corals,  again  (fig.  44),  consist  of  a  greater 
or  less  number  of  structures  similar  in  structure  to  the  above, 


IO4 


HISTORICAL   PALAEONTOLOGY. 


but  united  together  in  different  ways  into  a  common   mass. 
Simple  corals,  therefore,  are  the  skeletons  of  single  and  inde- 


Fig.    43.  —  Zaphrentis   Siokesi.    a    simple  Fig.   44. — Upper  surface  of  a  mass  of 

"cup-coral,"  Upper  Silurian,  Canada.    (After      Strombodes  pentagonus,   Upper  Silurian, 
Billings.)  Canada.     (After  Billings.) 

pendent  polypes ;  whilst  compound  corals  are  the  skeletons  of 
assemblages  or  colonies  of  similar  polypes,  living  united  with 
one  another  as  an  organic  community. 

In  the  general  details  of  their  structure,  the  Lower  Silurian 
Corals  do  not  differ  from  the  ordinary  Corals  of  the  present 
day.  The  latter,  however,  have  the  vertical  calcareous  plates 
of  the  coral  ("  septa  ")  arranged  in  multiples  of  six  or  five ; 
whereas  the  former  have  these  structures  arranged  in  multiples 
of  four,  and  often  showing  a  cross-like  disposition.  For  this 
reason,  the  common  Lower  Silurian  Corals  are  separated  to 
form  a  distinct  group  under  the  name  of  Rugose  Corals  or 
Rugosa.  They  are  further  distinguished  by  the  fact  that  the 
cavity  of  the  coral  ("  visceral  chamber  ")  is  usually  subdivided 
by  more  or  less  numerous  horizontal  calcareous  plates  or 
partitions,  which  divide  the  coral  into  so  many  tiers  or  storeys, 
and  which  are  known  as  the  "  tabulae"  (fig.  45). 

In  addition  to  the  Rugose  Corals,  the  Lower  Silurian  rocks 
contain  a  number  of  curious  compound  corals,  the  tubes 
of  which  have  either  no  septa  at  all  or  merely  rudimentary 
ones,  but  which  have  the  transverse  partitions  or  "  tabulae  " 
very  highly  developed.  These  are  known  as  the  Tabulate 
Corals  ;  and  recent  researches  on  some  of  their  existing  allies 
(such  as  Hclicpora]  have  shown  that  they  are  really  allied  to 


THE   LOWER   SILURIAN    PERIOD.  105 

the  modern    Sea-pens,    Organ-pipe    Corals,    and    Red   Coral, 
rather  than  to  the  typical  stony  Corals.     Amongst  the  charac- 


Fig.  45. — Columnnria  ahieolata,  a  Rugose  compound  coral,  with  imperfect  septa,  but 
having  the  corallites  partitioned  off  into  storeys  by  "  tabulae."  Lower  Silurian,  Canada, 
f  Aftpr  R;IK.IO-C  \ 


(After  Billings.) 

teristic  Rugose  Corals  of  the  Lower  Silurian  may  be  mentioned 
species  belonging  to  the  genera  Columnaria,  Favistella,  Strep- 
telasma,  and  Zaphrentis ;  whilst  amongst  the  "  Tabulate " 
Corals,  the  principal  forms  belong  to  the  genera  Chatetes^ 
Halysites  (the  Chain-coral),  Constellaria,  and  Heliolites.  These 
groups  of  the  Corals,  however,  attain  a  greater  development 
at  a  later  period,  and  they  will  be  noticed  more  particularly 
hereafter. 

Passing  on  to  higher  animals,  we  find  that  the  class  of  the 
Echinodermata  is  represented  by  examples  of  the  Star-fishes 
(Asteroided],  the  Sea-lilies  (Cnnotdea),  and  the  peculiar  extinct 
group  of  the  Cystideans  (Cystoidea)^  with  one  or  two  of  the 
Brittle-stars  ( Ophiuroided) — the  Sea-urchins  (Echinoided)  being 
still  wanting.  The  Crinoids,  though  in  some  places  extremely 
numerous,  have  not  the  varied  development  that  they  possess 
in  the  Upper  Silurian,  in  connection  with  which  their  structure 
will  be  more  fully  spoken  of.  In  the  meanwhile,  it  is  sufficient 
to  note  that  many  of  the  calcareous  deposits  of  the  Lower 
Silurian  are  strictly  entitled  to  the  name  of  "  Crinoidal  lime- 
stones," being  composed  in  great  part  of  the  detached  joints, 
and  plates,  and  broken  stems,  of  these  beautiful  but  fragile 
organisms  (see  fig.  12).  Allied  to  the  Crinoids  are  the  singular 
creatures  which  are  known  as  Cystideans  (fig.  46).  These  are 
generally  composed  of  a  globular  or  ovate  body  (the  "  calyx  "), 
supported  upon  a  short  stalk  (the  "  column "),  by  which  the 
organism  was  usually  attached  to  some  foreign  body.  The 
body  was  enclosed  by  closely-fitting  calcareous  plates,  accu- 


io6 


HISTORICAL   PALEONTOLOGY. 


rately  jointed  together ;  and  the  stem  was  made  up  of  numerous 
distinct  pieces  or  joints,  flexibly  united  to  each  other  by  mem- 


Fig.  46.  — Group  of  Cystideans.  A,  Caryocrinus  ornatus,*  Upper  Silurian,  America; 
B,  Pleurocystites  squamosns,  showing  two  short  "arms,"  Lower  Silurian,  Canada;  C, 
Pseudocrinus  bifasciatus,  Upper  Silurian,  England  ;  D,  Lepatiocrinns  Gebhanii,  Upper 
Silurian,  America.  (After  Hall,  Billings,  and  Salter.) 

brane.  The  chief  distinction  which  strikes  one  in  comparing 
the  Cystideans  with  the  Crinoids  is,  that  the  latter  are  always 
furnished,  as  will  be  subsequently  seen,  with  a  beautiful  crown 
of  branched  and  feathery  appendages,  springing  from  the  sum- 
mit of  the  calyx,  and  which  are  composed  of  innumerable 
calcareo'us  plates  or  joints,  and  are  known  as  the  "  arms."  In 
the  Cystideans,  on  the  other  hand,  there  are  either  no  "  arms  " 
at  all,  or  merely  short,  unbranched,  rudimentary  arms.  The 
Cystideans  are  principally,  and  indeed  nearly  exclusively, 
Silurian  fossils ;  and  though  occurring  in  the  Upper  Silurian 
in  no  small  numbers,  they  are  pre-eminently  characteristic  of 
the  Llandeilo-Caradoc  period  of  Lower  Silurian  time.  They 
commenced  their  existence,  so  far  as  known,  in  the  Upper 
Cambrian ;  and  though  examples  are  not  absolutely  unknown 

*  The  genus  Caryocrinus  is  sometimes  regarded  as  properly  belonging 
to  the  Crinoids,  but  there  seem  to  be  good  reasons  for  rather  considering 
it  as  an  abnormal  form  of  Cvstidean. 


THE   LOWER   SILURIAN    PERIOD. 


ID/ 


in  later  periods,  they  are  pre-eminently  characteristic  of  the 
earlier  portion  of  the  Palaeozoic  epoch. 

The  Ringed  Worms  (Annelides]  are  abundantly  represented 
in  the  Lower  Silurian,  but  principally  by  tracks  and  burrows 
similar  in  essential  respects  to  those  which  occur  so  commonly 
in  the  Cambrian  formation,  and  calling  for  no  special  com- 
ment. Much  more  important  are  the  Articulate  animals,  rep- 
resented, as  heretofore,  wholly  by  the  remains  of  the  aquatic 


Fig.  47. — Lower  Silurian  Crustaceans,  a,  Asaphus  tyrannies,  Upper  Llandeilo  ;  b, 
Ogygia  Buchii,  Upper  Llandeilo  ;  c,  Trimtclens  concentricus,  Caradoc  ;  d,  Caryocaris 
Wrightii,  Arenig  (Skiddaw  Slates) ;  e,  Beyrichia  cornplicata^  natural  size  and  enlarged, 
Upper  Llandeilo  and  Caradoc ;  f,  Ptimitia  strangulata,  Caradoc :  £•,  Head-shield  of 
Calymene  Biumenbachii,  var.  brevicapitata,  Caradoc  ;  h,  Head-shield  of  Triarthrus 
Becki  (Utica  Slates),  United  States  ;  i,  Shield  of  Leperditia  Canadensis,  var.  Joseph- 
iana,  of  the  natural  size,  Trenton  Limestone,  Canada ;  /,  The  same,  viewed  from  the 
front.  (After  Salter,  M'Coy,  Rupert  Jones,  and  Dana.) 

group  of  the  Crustaceans.     Amongst  these  are  numerous  little 
bivalved  forms — such  as  species  of  Primitia  (fig.  47,  /),  Bey- 


108  HISTORICAL   PALEONTOLOGY. 

richia  (fig.  47,  <?),  and  Lepcrditia  (fig.  47,  /  and  j).  Most  of 
these  are  very  small,  varying  from  the  size  of  a  pin's  head  up 
to  that  of  a  hemp  seed ;  but  they  are  sometimes  as  large  as 
a  small  bean  (fig.  47,  /),  and  they  are  commonly  found  in 
myriads  together  in  the  rock.  As  before  said,  they  belong  to 
the  same  great  group  as  the  living  Water-fleas  (Ostracoda). 
Besides  these,  we  find  the  pod-shaped  head-shields  of  the 
shrimp-like  Phyllopods — such  as  Caryocaris  (fig.  47,  d)  and 
Ceratiocaris.  More  important,  however,  than  any  of  these  are 
the  Trilobites,  which  may  be  considered  as  attaining  their  maxi- 
mum development  in  the  Lower  Silurian.  The  huge  Paradoxides 
of  the  Cambrian  have  now  disappeared,  and  with  them  almost 
all  the  principal  and  characteristic  "  primordial "  genera,  save 
Olenus  and  Agnostus.  In  their  place  we  have  a  great  number 
of  new  forms — some  of  them,  like  the  great  A saphus  tyrannus 
of  the  Upper  Llandeilo  (fig.  47,  a),  attaining  a  length  of  a  foot 
or  more,  and  thus  hardly  yielding  in  the  matter  of  size  to  their 
ancient  rivals.  Almost  every  subdivision  of  the  Lower  Silurian 
series  has  its  own  special  and  characteristic  species  of  Trilo- 
bites ;  and  the  study  of  these  is  therefore  of  great  importance 
to  the  geologist.  A  few  widely-dispersed  and  characteristic 
species  have  been  here  figured  (fig.  47) ;  and  the  following 
may  be  considered  as  the  principal  Lower  Silurian  genera — 
A  saphus j  Ogygia,  Cheirurus,  Ampyx,  Calymene,  Trinucleus, 
Lichas,  Illcenus,  ALglina,  Harpes,  Remopleurides,  Phacops, 
AridaspiS)  and  Homalonotus,  a  few  of  them  passing  upwards 
under  new  forms  into  the  Upper  Silurian. 

Coming  next  to  the  Mollusca,  we  find  the  group  of  the  Sea- 
mosses  and  Sea-mats  (Polyzoa}  represented  now  by  quite  a 
number  of  forms.  Amongst  these  are  examples  of  the  true 
Lace-corals  (Retepora  and  Fenestclld),  with  their  netted  fan-like 
or  funnel-shaped  fronds ;  and  along  with  these  are  numerous 
delicate  encrusting  forms,  which  grew  parasitically  attached  to 
shells  and  corals  (Hippothoa,  Alecto,  &c.);  but  perhaps  the 
most  characteristic  forms  belong  to  the  genus  Ptilodictya  (figs. 
48  and  49).  In  this  group  the  frond  is  flattened,  with  thin 
striated  edges,  sometimes  sword-like  or  scimitar-shaped,  but 
often  more  or  less  branched  ;  and  it  consists  of  two  layers  of 
cells,  separated  by  a  delicate  membrane,  and  opening  upon 
opposite  sides.  Each  of  these  little  chambers  or  "  cells"  was 
originally  tenanted  by  a  minute  animal,  and  the  whole  thus 
constituted  a  compound  organism  or  colony. 

The  Lamp-shells  or  Brachiopods  are  so  numerous,  and  pre- 
sent such  varied  types,  both  in  this  and  the  succeeding  period 
of  the  Upper  Silurian,  that  the  name  of  "  Age  of  Brachiopods" 


THE  .LCAYER    SILURIAN    PERIOD. 


109 


has  with  justice  been  applied  to  the  Silurian  period  as  a  whole. 
It  would  be  impossible  here  to  enter  into  details  as  to  the 


Fig.  48. — Ptilodictya  falciformis.  a, 
Small  specimen  of  the  natural  size ;  b, 
Cross-section,  showing  the  shape  of  the 
frond  ;  c,  Portion  of  the  surface,  enlarged. 
Trenton  Limestone  and  Cincinnati  Group, 
America.  (Original.) 


a 


Fig.  49.— A,  Ptilodictya  acida  ;  B,  Ptil- 
odictya Schafferi.  a,  Fragment,  of  the 
natural  size  ;  b,  Portion,  enlarged  to  show 
the  cells.  Cincinnati  Group  of  Ohio  and 
Canada.  (Original.) 


many  different  forms  of  Brachiopods  which  present  themselves 
in  the  Lower  Silurian  deposits ;  but  we  may  select  the  three 
genera  Orthis,  Strophomena,  and  Leptcena  for  illustration,  as 
being  specially  characteristic  of  this  period,  though  not  exclu- 


Fig.  50. — -Lower  Silurian  Brachiopods.  ft  and  a',  Orthis  biforata,  Llandeilo-Caradoc, 
Britain  and  America  ;  b,  Orthis  Jlabelluiiim.  Caradoc,  Britain  ;  <r,  Orthis  subquadrata, 
Cincinnati  Group,  America  ;  c',  Interior  of  the  dorsal  valve  of  the  same  ;  d,  Stropho- 
mena deltoidea,  Llandeilo-Caradoc.  Britain  and  America.  (After  Meek,  Hall,  and 
Salter.) 

sively  confined  to  it.     The  numerous  shells  which  belong  to 
the  extensive  and  cosmopolitan  genus  Orthis  (fig.  50,  a,  b,  c, 
9 


I  IO 


HISTORICAL   PALEONTOLOGY. 


and  fig.  51,  c  and  d\  are   usually   more  or  less  transversely- 
oblong  or  subquadrate,  the  two  valves  (as  more  or  less  in  all 


Fig.  51. — Lower  Silurian  Brachiopods.  a,  Strophomena  alternata,  Cincinnati  Group, 
America  ;  b.  Strof>homenafilitexta,  Trenton  and  Cincinnati  Groups,  America  ;  c,  Orthis 
testudinaria,  Caradoc,  Europe,  and  America;  d,  d ',  Orthis  plicatella,  Cincinnati 
Group,  America  ;  e,  e'.  e",  Leptiena  sericen,  Llandeilo  and  Caradoc,  Europe  and  Ame- 
rica. (After  Meek,  Hall,  and  the  Author.) 

the  Brachiopods)  of  unequal  sizes,  generally  more  or  less  con- 
vex, and  marked  with  radiating  ribs  or  lines.  The  valves  of 
the  shell  are  united  to  one  another  by  teeth  and  sockets,  and 
there  is  a  straight  hinge-line.  The  beaks  are  also  separated 
by  a  distinct  space  ("hinge-area"),  formed  in  part  by  each 
valve,  which  is  perforated  by  a  triangular  opening,  through 
which,  in  the  living  condition,  passed  a  muscular  cord  attach- 
ing the  shell  to  some  foreign  object.  The  genus  Strophomena 
(fig.  50,  d,  and  51,  a  and  It)  is  very  like  Orthis  in  general  char- 
acter ;  but  the  shell  is  usually  much  flatter,  one  or  other  valve 
often  being  concave,  the  hinge-line  is  longer,  and  the  aperture 
for  the  emission  of  the  stalk  of  attachment  is  partially  closed 
by  a  calcareous  plate.  In  Lepttcna,  again  (fig.  51,  e),  the  shell 
is  like  Stroph&tnena  in  many  respects,  but  generally  compara- 
tively longer,  often  completely  semicircular,  and  having  one 
valve  convex  and  the  other  valve  concave.  Amongst  other 
genera  of  Brachiopods  which  are  largely  represented  in  the 
Lower  Silurian  rocks  may  be  mentioned  Lingula,  Cranr, 
Discina,  Trematis,  Siphonotreta,  Acrotreta,  Rhynchondla,  and 
Athyris  ;  but  none  of  these  can  claim  the  importance  to  which 
the  three  previously-mentioned  groups  are  entitled. 

The  remaining  Lower  Silurian  groups  of  Mollusca  can  be 
but  briefly  glanced  at  here.  The  Bivalves  (Lamellibranchiata) 
find  numerous  representatives,  belonging  to  such  genera  as 


THE   LOWER   SILURIAN    PERIOD. 


Ill 


Modiolopsis,  Ctenodonta;  Orthonota,  Palaarca,  Lyrodesma,  Am- 
bonychia,  and  Cleidophorus.  The  Univalves  (Gasteropoda)  are 
also  very  numerous,  the  two  most  important  genera  being 
Murchisonia(^.  52)  and  Pleurotomaria.  In  both  these  groups 
the  outer  lip  of  the  shell  is  notched  ;  but  the  shell 
in  the  former  is  elongated  and  turreted,  whilst  in 
the  latter  it  is  depressed.  The  curious  oceanic 
Univalves  known  as  the  Heteropods  are  also  very 
abundant,  the  principal  forms  belonging  to  Bel- 
lerophon  and  Madurea.  In  the  former  (fig.  53) 
there  is  a  symmetrical  convoluted  shell,  like  that 
of  the  Pearly  Nautilus  in  shape,  but  without  any 
internal  partitions,  and  having  the  aperture  of- 
ten expanded  and  notched  behind.  The  species 
of  Madurea  (fig.  54)  are  found  both  in  North 
America  and  in  Scotland,  and  are  exclusively 
confined  to  the  Lower  Silurian  period,  so  far 
as  known.  They  have  the  shell  coiled  into  a 
flat  spiral,  the  mouth  being  furnished  with  a 
very  curious,  thick,  and  solid  lid  or  "opercu- 
lum."  The  Lower  Silurian  Pteropods,  or  "Wing- 
ed Snails,"  are  numerous,  and  belong  principally 
to  the  genera  Theca,  Conularia,  and  Tentaculitcs, 
the  last-mentioned  of  these  often  being  extremely  abundant  in 
certain  strata. 

Lastly,  the  Lower  Silurian  Rocks  have  yielded  a  vast  number 


Fig.  52. — Mur- 
chisonia  gracilis, 
Trenton  Lime- 
stone, America. 
(After  Billings.) 


Fig-  53-— Different  views  of  Bellerofihon  A  rgo,  Trenton  Limestone,  Canada. 
(After  Billings.) 

of  chambered  shells,  referable  to  animals  which  belong  to  the 
same  great  division  as  the  Cuttle-fishes  (the  Cephalopoda),  and 
of  which  the  Pearly  Nautilus  is  the  only  living  representative  at 
the  present  day.  In  this  group  of  Cephalopods  the  animal 
possesses  a  well-developed  external  shell,  which  is  divided 
into  chambers  by  shelly  partitions  ("  septa ").  The  animal 
lives  in  the  last-formed  and  largest  chamber  of  the  shell,  to 


112  HISTORICAL   PALEONTOLOGY. 

which  it  is  organically  connected  by  muscular  attachments. 
The  head  is  furnished  with  long  muscular  processes  or  "arms/' 


Fig.  54.—  Different  views  of  Maclnrca  crenulata,  Quebec  Group,  Newfoundland. 
(After  Billings.) 

and  can  be  protruded  from  the  mouth  of  the  shell  at  will,  or 
again  withdrawn  within  it.  We  learn,  also,  from  the  Pearly 
Nautilus,  that  these  animals  must  have  possessed  two  pairs  of 
breathing  organs  or  "  gills  ; "  hence  all  these  forms  are  grouped 
together  under  the  name  of  the  "  Tetrabranchiate  "  Cephalo- 
pods  (Gr.  tetra,  four;  bragchia,  gill).  On  the  other  hand,  the 
ordinary  Cuttle-fishes  and  Calamaries  either  possess  an  internal 
skeleton,  or  if  they  have  an  external  shell,  it  is  not  chambered  ; 
their  "arms"  are  furnished  with  powerful  organs  of  adhesion 
in  the  form  of  suckers ;  and  they  possess  only  a  single  pair  of 
gills.  For  this  last  reason  they  are  termed  the  "  Dibranchiate  " 
Cephalopods  (Gr.  dis,  twice ;  bragchia,  gill).  No  trace  of  the 
true  Cuttle-fishes  has  yet  been  found  in  Lower  Silurian  deposits; 
but  the  Tetrabranchiate  group  is  represented  by  a  great  num- 
ber of  forms,  sometimes  of  great  size.  The  principal  Lower 
Silurian  genus  is  the  well-known  and  widely-distributed  Ortho- 
ceras  (fig.  55).  The  shell  in  this  genus  agrees  with  that  of  the 
existing  Pearly  Nautilus,  in  consisting  of  numerous  chambers 
separated  by  shelly  partitions  (or  septa),  the  latter  being  per- 
forated by  a  tube  which  runs  the  whole  length  of  the  shell 
after  the  last  chamber,  and  is  known  as  the  "  siphuncle  "  (fig. 
56,  s).  The  last  chamber  formed  is  the  largest,  and  in  it  the 
animal  lives.  The  chambers  behind  this  are  apparently  filled 
with  some  gas  secreted  by  the  animal  itself;  and  these  are  sup- 
posed to  act  as  a  kind  of  float,  enabling  the  creature  to  move 
with  ease  under  the  weight  of  its  shell.  The  various  air- 
chambers,  though  the  siphuncle  passes  through  them,  have  no 
direct  connection  with  one  another;  and  it  is  believed  that  the 
animal  has  the  power  of  slightly  altering  its  specific  gravity, 
and  thus  cf  rising  or  sinking  in  the  water  by  driving  additional 
fluid  into  the  siphuncle  or  partially  emptying  it.  The  Ortho- 


THE   LOWER  SILURIAN   PERIOD. 


ceras  further  agrees  with  the  Pearly  Nautilus  in  the  fact  that 
the  partitions  or  septa  separating  the  different  air-chambers  are 


Fig-  55- — Fragment  of  Orthoceras  crebri- 
septutn,  Cincinnati  Group,  North  America, 
of  the  natural  size.  The  lower  figure  is  a 
section  showing  the  air-chambers,  and  the 
form  and  position  of  the  siphuncle.  (After 
Billings.) 


Fig.  56.  — Restoration  of  Orthoceras^ 
the  shell  being  supposed  to  be  divided  ver- 
tically, and  only  its  upper  part  being 
shown,  a,  Arms  ;  f,  Muscular  tube 
("funnel")  by  which  water  is  expelled 
from  the  mantle-chamber;  c,  Air-cham- 
bers ;  s,  Siphuncle. 


simple  and  smooth,  concave  in  front  and  convex  behind,  and 
devoid  of  the  elaborate  lobation  which  they  exhibit  in  the 
Ammonites ;  whilst  the  siphuncle  pierces  the  septa  either  in 
the  centre  or  near  it.  In  the  Nautilus,  however,  the  shell  is 
coiled  into  a  flat  spiral ;  whereas  in  Orthoceras  the  shell  is  a 
straight,  longer  or  shorter  cone,  tapering  behind,  and  gradu- 
ally expanding  towards  its  mouth  in  front  The  chief  objec- 
tions to  the  belief  that  the  animal  of  the  Orthoceras  was  essen- 
tially like  that  of  the  Pearly  Nautilus  are — the  comparatively 
small  size  of  the  body-chamber,  the  often  contracted  aperture 
of  the  mouth,  and  the  enormous  size  of  some  specimens  of 

*  This  illustration  is  taken  from  a  rough  sketch  made  by  the  author 
many  years  ago,  but  he  is  unable  to  say  from  what  original  source  it  was 
copied. 


114  HISTORICAL   PALEONTOLOGY. 

the  shell.  Thus,  some  Orthocei\~:ta  have  been  discovered 
measuring  ten  or  twelve  feet  in  length,  with  a  diameter  of  a 
foot  at  the  larger  extremity.  These  colossal  dimensions  cer- 
tainly make  it  difficult  to  imagine  that  the  comparatively  small 
body-chamber  could  have  held  an  animal  large  enough  to  move 
a  load  so  ponderous  as  its  own  shell.  To  some,  this  difficulty 
has  appeared  so  great  that  they  prefer  to  believe  that  the 
Orthoceras  did  not  live  in  its  shell  at  all,  but  that  its  shell  was 
an  internal  skeleton  similar  to  what  we  shall  find  to  exist  in 
many  of  the  true  Cuttle-fishes.  There  is  something  to  be  said 
in  favour  of  this  view,  but  it  would  compel  us  to  believe  in  the 
existence  in  Lower  Silurian  times  of  Cuttle-fishes  fully  equal 
In  size  to  the  giant  "Kraken"  of  fable.  It  need  only  be 
added  in  this  connection  that  the  Lower  Silurian  rocks  have 
yielded  the  remains  of  many  other  Tetrabranchiate  Cephalo- 
pods  besides  Orthoceras.  Some  of  these  belong  to  Cyrtoceras, 
which  only  differs  from  Orthoceras  in  the  bow-shaped  form  of 
the  shell ;  others  belong  to  Phragmoceras,  Lituites,  &c. ;  and, 
hstly,  we  have  true  Nautili,  with  their  spiral  shells,  closely 
resembling  the  existing  Pearly  Nautilus. 

Whilst  all  the  sub-kingdoms  of  the  Invertebrate  animals  are 
represented  in  the  Lower  Silurian  rocks,  no  traces  of  Verte- 
brate animals  have  ever  been  discovered  in  these  ancient 
deposits,  unless  the  so-called  "  Conodonts"  found  by  Pander 
in  vast  numbers  in  strata  of  this  age  *  in  Russia  should  prove 
to  be  really  of  this  nature.  These  problematical  bodies  are  of 
microscopic  size,  and  have  the  form  of  minute,  conical,  tooth- 
shaped  spines,  with  sharp  edges,  and  hollow  at  the  base. 
Their  original  discoverer  regarded  them  as  the  horny  teeth 
of  fishes  allied  to  the  Lampreys ;  but  Owen  came  to  the  con- 
clusion that  they  probably  belonged  to  Invertebrates.  The 
recent  investigation  of  a  vast  number  of  similar  but  slightly 
larger  bodies,  of  very  various  forms,  in  the  Carboniferous  rocks 
of  Ohio,  has  led  Professor  Newberry  to  the  conclusion  that 
these  singular  fossils  really  are,  as  Pander  thought,  the  teeth  of 
Cyclostomatous  fishes.  The  whole  of  this  difficult  question 
has  thus  been  reopened,  and  we  may  yet  have  to  record  the 
first  advent  of  Vertebrate  animals  in  the  Lower  Silurian. 

*  According  to  Pander,  the  "Conodonts"  are  found  not  only  in  the 
Lower  Silurian  beds,  but  also  in  the  "  Ungulite  Grit  "  (Upper  Cambrian), 
as  well  as  in  the  Devonian  and  Carboniferous  deposits  of  Russia.  Should 
the  Conodonts  prove  to  be  truly  the  remains  of  fishes,  we  should  thus  have 
to  transfer  the  first  appearance'  of  Vertebrates  to,  at  any  rate,  as  early  a 
period  as  the  Upper  Cambrian. 


THE   UPPER   SILURIAN    PERIOD.  115 

CHAPTER    X. 
THE    UPPER   SILURIAN  PERIOD. 

Having  now  treated  of  the  Lower  Silurian  period  at  consider- 
able length,  it  will  not  be  necessary  to  discuss  the  succeeding 
group  of  the  Upper  Silurian  in  the  same  detail — the  more  so, 
as  with  a  general  change  of  species  the  Upper  Silurian  animals 
belong  for  the  most  part  to  the  same  great  types  as  those  which 
distinguish  the  Lower  Silurian.  As  compared,  also,  as  regards 
the  total  bulk  of  strata  concerned,  the  thickness  of  the  Upper 
Silurian  is  generally  very  much  below  that  of  the  Lower  Silurian, 
indicating  that  they  represent  a  proportionately  shorter  period 
of  time.  In  considering  the  general  succession  of  the  Upper 
Silurian  beds,  we  shall,  as  before,  select  Wales  and  America  as 
being  two  regions  where  these  deposits  are  typically  developed. 

In  Wales  and  its  borders  the  general  succession  of  the 
Upper  Silurian  rocks  may  be  taken  to  be  as  follows,  in  ascend- 
ing order  (fig.  57):— 

(1)  The  base  of  the  Upper  Silurian  series  is  constituted  by 
a  series  of  arenaceous  beds,  to  which  the  name  of  "  May  Hill 
Sandstone  "  was  applied  by  Sedgwick.     These  are  succeeded 
by  a  series  of  greenish-grey  or  pale-grey  slates  ("  Tarannon 
Shales"),  sometimes  of  great  thickness;  and  these  two  groups 
of  beds  together  form  what  may  be  termed  the  "May  Hill 
Group"  (Upper  Llandovery  of  Murchison).     Though  not  very 
extensively  developed  in  Britain,  this  zone  is  one  very  well 
marked  by  its  fossils ;  and  it  corresponds  with  the  "  Clinton 
Group"  of  North  America,  in  which  similar  fossils  occur.     In 
South  Wales  this  group  is  clearly  unconformable  to  the  highest 
member  of  the  subjacent  Lower  Silurian  (the  Llandovery  group); 
and  there  is  reason  to  believe  that  a  similar,  though  less  con- 
spicuous,  physical  break  occurs  very  generally  between  the 
base  of  the  Upper  and  the  summit  of  the  Lower  Silurian. 

(2)  The  Wenlock  Group  succeeds  the  May  Hill  group,  and 
constitutes  the  middle  member  of  the  Upper  Silurian.     At  its 
base  it  may  have  an  irregular  limestone  ("Woolhope  Lime- 
stone"), and  its  summit  maybe  formed  by  a  similar  but  thicker 
calcareous  deposit  ("Wenlock  Limestone");  but  the  bulk  of  the 
group  is  made  up  of  the  argillaceous  and  shaly  strata  known  as 
the  "  Wenlock  Shale."     In  North  Wales  the  Wenlock  group  is 
represented  by  a  great  accumulation  of  flaggy  and  gritty  strata 
(the  "Denbighshire  Flags  and  Grits"),  and  similar  beds  (the 


Il6  HISTORICAL   PALAEONTOLOGY. 

"  Coniston  Flags  "  and  "  Coniston  Grits  ")  take  the  same  place 
in  the  north  of  England. 

(3)  The  Ludlow  Group  is  the  highest  member  of  the  Upper 
Silurian,  and  consists  typically  of  a  lower  arenaceous  and  shaly 
series  (the  "Lower  Ludlow  Rock")  a  middle  calcareous 
member  (the  "  Aymestry  Limestone"),  and  an  upper  shaly  and 
sandy  series  (the  "  Upper  Ludlow  Rock  "  and  "  Downton  Sand- 
stone"). At  the  summit,  or  close  to  the  summit,  of  the  Upper 
Ludlow,  is  a  singular  stratum  only  a  few  inches  thick  (vary- 
ing from  an  inch  to  a  foot),  which  contains  numerous  remains 
of  crustaceans  and  fishes,  and  is  well  known  under  the  name 
of  the  "bone-bed."  Finally,  the  Upper  Ludlow  rock  graduates 
invariably  into  a  series  of  red  sandy  deposits,  which,  when  of 
a  flaggy  character,  are  known  locally  as  the  "Tile-stones." 
These  beds  are  probably  to  be  regarded  as  the  highest  member 
of  the  Upper  Silurian  ;  but  they  are  sometimes  looked  upon  as 
passage-beds  into  the  Old  Red  Sandstone,  or  as  the  base  of 
this  formation.  It  is,  in  fact,  apparently  impossible  to  draw 
any  actual  line  of  demarcation  between  the  Upper  Silurian  and 
the  overlying  deposits  of  the  Devonian  or  Old  Red  Sandstone 
series.  Both  in  Britain  and  in  America  the  Lower  Devonian 
beds  repose  with  perfect  conformity  upon  the  highest  Silurian 
beds,  and  the  two  formations  appear  to  pass  into  one  another 
by  a  gradual  and  imperceptible  transition. 

The  Upper  Silurian  strata  of  Britain  vary  from  perhaps 
3000  or  4000  feet  in  thickness  up  to  8000  or  io,oco  feet.  In 
North  America  the  corresponding  series,  though  also  variable, 
is  generally  of  much  smaller  thickness,  and  may  be  under  1000 
feet.  The  general  succession  of  the  Upper  Silurian  deposits 
of  North  America  is  as  follows  :  — 

(1)  Medina  Sandstone. — This   constitutes  the   base  of  the 
Upper  Silurian,  and  consists  of  sandy  strata,  singularly  devoid 
of  life,  and  passing  below  in  some  localities  into  a  conglo- 
merate ("  Oneida  Conglomerate  "),  which  is  stated  to  contain 
pebbles  derived  from  the  older  beds,  and  which  would  thus 
indicate    an    unconformity    between    the    Upper   and    Lower 
Silurian. 

(2)  Clinton    Group.  —  Above    the    Medina    sandstone    are 
beds  of  sandstone  and  shale,  sometimes  with  calcareous  bands, 
which  constitute  what  is  known  as  the  "  Clinton  Group."     The 
Medina  and  Clinton  groups  are  undoubtedly  the  equivalent  of 
the  "  May  Hill  Group  "  of  Britain,  as  shown  by  the  identity  of 
their  fossils. 


THE   UPPER   SILURIAN    PERIOD. 


II/ 


GENERALISED  SECTION  OF  THE  UPPER  SILURIAN  STRATA 
OF  WALES  AND  SHROPSHIRE. 


Fig.  57- 


Base  of  Old   Red    Sand- 
stone. 


Tile-stones. 

—  Upper  Ludlow  Rock. 

—  Aymestry  Limestone. 

Lower  Ludlow  Rock. 

Wenlock  Limestone. 

I  Wenlock  Shale  (Denbigh- 

J      shire  Flags  and  Grits  of 

(      North  Wales). 

Woolhope  Limestone. 

Tarannon  Shales. 
May  Hill  Sandstone. 

Llandovery  Rocks. 


(3)  Niagara   Group. — This   group   consists    typically  of  a 
series    of  argillaceous   beds    ("  Niagara    Shale")    capped   by 
limestones  ("Niagara    Limestone");    and    the    name  of  the 
group  is  derived  from  the  fact  that  it  is  over  limestones  of  this 
age  that  the   Niagara  river  is  precipitated  to  form  the  great 
Falls.      In  places  the   Niagara   group  is  wholly  calcareous, 
and  it  is  continued  upwards  into  a  series  of  marls  and  sand- 
stones, with  beds  of  salt  and  masses  of  gypsum  (the  "  Salina 
Group  "),  or  into  a  series  of  magnesian  limestones  ("  Guelph 
Limestones  ").     The  Niagara  group,  as  a  whole,  corresponds 
unequivocally  with  the  Wenlock  group  of  Britain. 

(4)  Lower  Helderberg  Group. — The  Upper  Silurian  period 
in  North  America  was  terminated  by  the  deposition  of  a  series 
of  calcareous  beds,  which  derive  the  name  of  "  Lower  Helder- 
berg" from  the  Helderberg  mountains,  south  of  Albany,  and 


IlS  HISTORICAL  PALEONTOLOGY. 

which  are  divided  into  several  zones,  capable  of  recognition  by 
their  fossils,  and  known  by  local  names  (Tentaculite  Lime- 
stone, Water-lime,  Lower  Pentamerus  Limestone,  Delthyris 
Shaly  Limestone,  and  Upper  Pentamerus  Limestone).  As  a 
whole,  this  series  may  be  regarded  as  the  equivalent  of  the 
Ludlow  group  of  Britain,  though  it  is  difficult  to  establish  any 
precise  parallelism.  The  summit  of  the  Lower  Helderberg 
group  is  constituted  by  a  coarse-grained  sandstone  (the  "  Oris- 
kany  Sandstone  "),  replete  with  organic  remains,  which  have 
to  a  large  extent  a  Silurian  fades.  Opinions  differ  as  to  whether 
this  sandstone  is  to  be  regarded  as  the  highest  bed  of  the  Upper 
Silurian  or  the  base  of  the  Devonian.  We  thus  see  that  in 
America,  as  in  Britain,  no  other  line  than  an  artificial  one  can  be 
drawn  between  the  Upper  Silurian  and  the  overlying  Devonian. 

As  regards  the  life  of  the  Upper  Silurian  period,  we  have,  as 
before,  a  number  of  so-called  "  Fucoids,"  the  true  vegetable 
nature  of  which  is  in  many  instances  beyond  doubt.  In  addi- 
tion to  these,  however,  we  meet  for  the  first  time,  in  deposits 
of  this  age,  with  the  remains  of  genuine  land-plants,  though 
our  knowledge  of  these  is  still  too  scanty  to  enable  us  to  con- 
struct any  detailed  picture  of  the  terrestrial  vegetation  of  the 
period.  Some  of  these  remains  indicate  the  existence  of  the 
remarkable  genus  Lepidodendron — a  genus  which  played  a  part 
of  great  importance  in  the  forests  of  the  Devonian  and  Carbon- 
iferous periods,  and  which  may  be  regarded  as  a  gigantic  and 
extinct  type  of  the  Club-mosses  (Lycopodiacece).  Near  the 
summit  of  the  Ludlow  formation  in  Britain  there  have  also 
been  found  beds  charged  with  numerous  small  globular  bodies, 
which  Dr  Hooker  has  shown  to  be  the  seed-vessels  or  "  spor- 
angia" of  Club-mosses.  Principal  Dawson  further  states  that 
he  has  seen  in  the  same  formation  fragments  of  wood  with  the 
structure  of  the  singular  Devonian  Conifer  known  as  Proto- 
taxites.  Lastly,  the  same  distinguished  observer  has  described 
from  the  Upper  Silurian  of  North  America  the  remains  of  the 
singular  land-plants  belonging  to  the  genus  Psilophyton,  which 
will  be  referred  to  at  greater  length  hereafter. 

The  marine  life  of  the  Upper  Silurian  is  in  the  main  con- 
stituted by  types  of  animals  similar  to  those  characterising  the 
Lower  Silurian,  though  for  the  most  part  belonging  to  different 
species.  The  Protozoans  are  represented  principally  by  Stro- 
matopora  and  Ischadites,  along  with  a  number  of  undoubted 
sponges  (such  as  Amphispongia,  Astrtzospongia,  Astylospongia, 
and  Palceomanori). 

Amongst  the  Coelenterates,  we  find  the  old  group  of  Grap- 
tolites  now  verging  on  extinction.  Individuals  still  remain 


THE   UPPER   SILURIAN   PERIOD. 


119 


B 


C 


numerous,  but  the  variety  of  generic  and  specific  types  has 
now  become  greatly  reduced.  All  the  branching  and  complex 
forms  of  the  Arenig,  the  twin-Grap- 
tolites  and  Dicranograpti  of  the 
Llandeilo,  and  the  double-celled 
Diplograpti  and  Climacograpti  of 
the  Bala  group,  have  now  disap- 
peared. In  their  place  we  have 
the  singular  Retiolites,  with  its  curi- 
ously-reticulated skeleton;  and  seve- 
ral species  of  the  single-celled  genus 
Monograptus,  of  which  a  character- 
istic species  (M.  priodon)  is  here 
figured.  If  we  remove  from  this 
group  the  plant-like  Dictyoncma, 
which  are  still  present,  and  which 
survive  into  the  Devonian,  no 
known  species  of  Graptolite  has 
hitherto  been  detected  in  strata 
higher  in  geological  position  than 
the  Ludlow.  This,  therefore,  pre- 
sents us  with  the  first  instance  we 
have  as  yet  met  with  of  the  total 
disappearance  and  extinction  of  a 
great  and  important  series  of  or- 
ganic forms. 

The  Corals  are  very  numerously 
represented  in  the  Upper  Silurian 
rocks,  some  of  the  limestones  (such 
as  the  Wenlock  Limestone)  being 
often  largely  composed  of  the  skeletons  of  these  animals. 
Almost  all  the  known  forms  of  this  period  belong  to  the 
two  great  divisions  of  the  Rugose  and  Tabulate  corals,  the 
former  being  represented  by  species  of  Zaphrentis,  Omphyma, 
Cystiphyllum,  Strombodes,  Acenmlaria,  Cyathophyllum,  &c. ; 
whilst  the  latter  belong  principally  to  the  genera  Favositcs, 
Chcetetes,  ffaly  sites,  Syringopora,  Hcliolites,  and .  Plasmopora. 
Amongst  the  Rugosa,  the -first  appearance  of  the  great  and 
important  genus  Cyathophyllum,  so  characteristic  of  the  Palae- 
ozoic period,  is  to  be  noted ;  and  amongst  the  Tabulata 
we  have  similarly  the  first  appearance,  in  force  at  any  rate, 
of  the  widely-spread  genus  Favosites  —  the  "  Honeycomb- 
corals."  The  "Chain-corals"  (Halysites},  figured  below  (fig.  59), 
are  also  very  common  examples  of  the  Tabulate  corals  during 
this  period,  though  they  occur  likewise  in  the  Lower  Silurian. 


Fig.  58. — A,  Monograptus  prio- 
dont  slightly  enlarged.  B,  Frag- 
ment of  the  same  viewed  from 
behind.  C,  Fragment  of  the  same 
viewed  in  front,  showing  the  mouths 
of  the  cellules.  D,  Cross-section 
of  the  same.  From  the  Wenlock 
Group  (Coniston  Flags  of  the  North 
of  England).  (Original.) 


120 


HISTORICAL   PALAEONTOLOGY. 


Amongst  the  Echinodermata,  all  those  orders  which  have 
hard  parts  capable   of  ready  preservation   are   more   or  less 


d 


Fig.  59.— a,  Halysites  cntennlaria,  small  variety,  of  the  natural  size  ;  b,  Fragment  of 
a  large  variety  of  the  same,  of  the  natural  size  ;  c,  Fragment  of  limestone  with  the  tubes 
of  Halysites  agglomerata,  of  the  natural  size  ;  d,  Vertical  section  of  two  tubes  of  the 
same,  showing  the  tabulae,  enlarged.  Niagara  Limestone  (Wenlock),  Canada.  (Original.) 

largely  represented.  We  have  no  trace  of  the  Holothurians 
or  Sea-cucumbers ;  but  this  is  not  surprising,  as  the  record  of 
the  past  is  throughout  almost  silent  as  to  the  former  existence 
of  these  soft-bodied  creatures,  the  scattered  plates  and  spicules 
in  their  skin  offering  a  very  uncertain  chance  of  preservation 
in  the  fossil  condition.  The  Sea-urchins  (Echinoids}  are  said 
to  be  represented  by  examples  of  the  old  genus  Pa/echinus. 
The  Star-fishes  (Asteroids]  and  the  Brittle- stars  (Ophiuroids) 
are,  comparatively  speaking,  largely  represented  ,  the  former 
by  species  of  Palasterina  (fig.  60),  PalcRctster  (fig.  60),  Palczo- 
coma  (fig.  60),  Petraster,  Glyptaster,  and  Lepidaster — and  the 
latter  by  species  of  Protaster  (fig.  61),  Palaodiscus,  Acroura, 
and  Eucladia.  The  singular  Cystideans,  or  "  Globe  Crinoids," 
with  their  globular  or  ovate,  tesselated  bodies  (fig.  46,  A,  C,  D.), 
are  also  not  uncommon  in  the  Upper  Silurian  ;  and  if  they  do 
not  become  finally  extinct  here,  they  certainly  survive  the  close 
of  this  period  by  but  a  very  brief  time.  13  y  far  the  most  im- 
portant, however,  of  the  Upper  Silurian  Echinoderms,  are  the 
Sea-lilies  or  Crinoids.  The  limestones  of  this  period  are  often 
largely  composed  of  the  fragmentary  columns  and  detached 


THE   UPPER   SILURIAN    PERIOD. 


121 


plates  of  these  creatures,  and  some  of  them  (such  as  the  Wen- 
lock  Limestone  of  Dudley)  have    yielded  perhaps  the  most 


Fig.  60.— Upper  Silurian  Star-fishes,  i,  Palasterina  primcrva,  Lower  Ludlow  ;  2, 
Palce'astcr  Rutkveni,  Lower  Ludlow ;  3,  PaUeocoma  Colvini,  Lower  Ludlow.  (After 
Sailer.) 

exquisitely-preserved  examples  of  this  group  with  which  we 
are  as  yet  acquainted.      However  varied  in  their  forms,  these 


Fig.  61. — A,  Protaster  SedgwicJcit,  showing  the  disc  and  bases  of  the  arms  ;  B,  Por- 
tion of  an  arm,  greatly  enlarged.     Lower  Ludlow.     (After  Salter.) 

beautiful  organisms  consist  of  a  globular,  ovate,  or  pear-shaped 
body  (the  "  calyx "),  supported  upon  a  longer  or  shorter 
jointed  stem  (or  "  column  ").  The  body  is  covered  externally 
with  an  armour  of  closely-fitting  calcareous  plates  (fig.  62),  and 
its  upper  surface  is  protected  by  similar  but  smaller  plates 
more  loosely  connected  by  a  leathery  integument.  From  the 
upper  surface  of  the  body,  round  its  margin,  springs  a  series 
of  longer  or  shorter  flexible  processes,  composed  of  innu- 
merable calcareous  joints  or  pieces,  movably  united  with  one 


122 


HISTORICAL   PALAEONTOLOGY. 


another.     The  arms  are  typically  five  in  number ;   but  they 
generally  subdivide  at  least  once,  sometimes  twice,  and  they 


Fig  62. — Upper  Silurian  Crinoids.  a,  Calyx  and  arms  of  Encalyptocrinus  polydacty- 
/HS,  Wenlock  Limestone  ;  b,  Ichthyocrinns  Icevis,  Niagara  Limestone,  America  ;  c, 
Taxocrmus  tuberculatus,  Wenlock  Limestone.  (After  M'Coy  and  Hall.) 

are  furnished  with  similar  but  more  slender  lateral  branches 
or  "  pinnules,"  thus  giving  rise  to  a  crown  of  delicate  feathery 
plumes.  The  "  column  "  is  the  stem  by  which  the  animal  is 
attached  permanently  to  the  bottom  of  the  sea ;  and  it  is  com- 
posed of  numerous  separate  plates,  so  jointed  together  that 
whilst  the  amount  of  movement  between  any  two  pieces  must 
be  very  limited,  the  entire  column  acquires  more  or  less  flexi- 
bility, allowing  the  organism  as  a  whole  to  wave  backwards  and 
forwards  on  its  stalk.  Into  the  exquisite  minutia  of  structure 
by  which  the  innumerable  parts  entering  into  the  composition 
of  a  single  Crinoid  are  adapted  for  their  proper  purposes  in 
the  economy  of  the  animal,  it  is  impossible  to  enter  here.  No 
period,  as  before  said,  has  yielded  examples  of  greater  beauty 
than  the  Upper  Silurian,  the  principal  genera  represented 
being  Cyathocrinus,  Platycrinus,  Marsupiocrinus,  Taxocrinus, 
Eucalyptocrinus,  Ichthyocrinus,  Mariacrinus,  Periechocrinus, 
Glyptocrinus,  Crotalocrinus,  and  Edriocrinus. 

The  tracks  and  burrows  of  Annelides  are  as  abundant  in 
the  Upper  Silurian  strata  as  in  older  deposits,  and  have  just 
as  commonly  been  regarded  as  plants.  The  most  abundant 
forms  are  the  cylindrical,  twisted  bodies  (Planohtes),  which  are 


THE    UPPER   SILURIAN    PERIOD. 


123 


so  frequently  found  on  the  surfaces  of  sandy  beds,  and  which 
have  been  described  as  the  stems  of  sea-weeds.  These  fossils 
(fig.  63),  however,  can  be  nothing  more,  in  most  cases,  than 


Fig.  63. — Planolites  vulgaris,  the  filled -up  burrows  of  a  marine  worm. 
Upper  Silurian  (Clinton  Group),  Canada.     (Original.) 

the  filled-up  burrows  of  marine  worms  resembling  the  living 
Lob-worms.  There  are  also  various  remains  which  belong  to 
the  group  of  the  tube-inhabiting  Annelides  (Tubicola).  Of 
this  nature  are  the  tubes  of  Serpulites  and  Cornulites,  and  the 
little  spiral  discs  of  Spirorbis  Leivisii. 

Amongst  the  Articulates,  we  still  meet  only  with  the  remains 
of  Crustaceans.  Besides  the  little  bivalved  Ostracoda — which 
here  are  occasionally  found  of  the  size  of  beans — and  various 
Phyllopods  of  different  kinds,  we  have  an  abundance  of  Trilo- 
bites.  These  last-mentioned  ancient  types,  however,  are  now 
beginning  to  show  signs  of  decadence  ;  and  though  still  indi- 
vidually numerous,  there  is  a  great  diminution  in  the  number 
of  generic  types.  Many  of  the  old  genera,  which  flourished 
so  abundantly  in  Lower  Silurian  seas,  have  now  died  out; 
and  the  group  is  represented  chiefly  by  species  of  Cheirurus, 
Encrinurus,  Harpes,  Praetus,  Lichas,  Acidaspis,  Illcenus,  Caly- 
me/ie,  Homalonotus,  and  Phacops — the  last  of  these,  one  of  the 


124 


HISTORICAL    PALEONTOLOGY. 


highest  and  most  beautiful  of  the  groups  of  Trilobites,  attaining 
here  its  maximum  of  development.  In  the  annexed  illustra- 
tion (fig.  64)  some  of  the  characteristic  Upper  Silurian  Trilo- 


Fig.  64. — Upper  Silurian  Trilobites.  a,  Cheirurus  bimucronatus,  Wenlock  and  Cara- 
doc;  b,  Phacops  longicaudalus,  Wenlock,  Britain,  and  America;  c,  Phacops  Downingice, 
Wenlock  and  Ludlow  ;  d,  Harpes  ungula,  Upper  Silurian,  Bohemia.  (After  Salter 
and  Barrande.) 

bites  are  represented — all,  however,  belonging  to  genera  which 
have  their  commencement  in  the  Lower  Silurian  period.  In 
addition  to  the  above,  the  Ludlow  rocks  of  Britain  and  the 
Lower  Helderberg  beds  of  North  America  have  yielded  the 
remains  of  certain  singular  Crustaceans  belonging  to  the 
extinct  order  of  the  Eurypterida.  Some  of  these  wonderful 
forms  are  not  remarkable  for  their  size ;  but  others,  such  as 
Pterygotus  Anglicus  (fig.  65),  attain  a  length  of  six  feet  or  more, 
and  may  fairly  be  considered  as  the  giants  of  their  class.  The 
Eurypterids  are  most  nearly  allied  to  the  existing  King-crabs 
(Limuti),  and  have  the  anterior  end  of  the  body  covered  with 
a  great  head-shield,  carrying  two  pairs  of  eyes,  the  one  simple 
and  the  other  compound.  The  feelers  are  converted  into 
pincers,  whilst  the  last  pair  of  limbs  have  their  bases  covered 
with  spiny  teeth  so  as  to  act  as  jaws,  and  are  flattened  and 
widened  out  towards  their  extremities  so  as  to  officiate  as 
swimming-paddles.  The  hinder  extremity  of  the  body  is  com- 
posed of  thirteen  rings,  which  have  no  legs  attached  to  them ; 
and  the  last  segment  of  the  tail  is  either  a  flattened  plate  or  a 


THE   UPPER   SILURIAN    PERIOD. 


12 


narrow,  sword-shaped  spine.  Fragments  of  the  skeleton  are 
easily  recognised  by  the  peculiar  scale-like  markings  with 
which  the  surface  is  adorned,  and 
which  look  not  at  all  unlike  the 
scales  of  a  fish.  The  most  fam- 
ous locality  for  these  great  Crus- 
taceans is  Lesmahagow,  in  Lan- 
arkshire, where  many  different 
species  have  been  found.  The 
true  King-crabs  (Limult)  of  exist- 
ing seas  also  appear  to  have  been 
represented  by  at  least  one  form 
(Neolimulus)  in  the  Upper  Silu- 
rian. 

Coming  to  the  Mottusca,  we 
note  the  occurrence  of  the  same 
great  groups  as  in  the  Lower 
Silurian.  Amongst  the  Sea- 
mosses  (Polyzod),  we  have  the 
ancient  Lace  -  corals  (Fenestella 
and  Retepora),  with  the  nearly- 
allied  Glaticonome,  and  species  of 
Ptilodiclya  (fig.  66) ;  whilst  many 
forms  often  referred  here  may 
probably  have  to  be  transferred 
to  the  Corals,  just  as  some  so- 
called  Corals  will  ultimately  be 
removed  to  the  present  group. 

The  Brachiopods  continued 
to  flourish  during  the  Upper 
Silurian  period  in  immense  num- 
bers and  under  a  greatly  in- 
creased variety  of  forms.  The  three  prominent  Lower 
Silurian  genera  Orlhis,  Strophomena,  and  Leptana  are  still 
well  represented,  though  they  have  lost  their  former  pre- 
eminence. Amongst  the  numerous  types  which  have  now 
come  upon  the  scene  for  the  first  time,  or  which  have  now  a 
special  development,  are  Spirifcra  and  Pentamenis.  In  the 
first  of  these  (fig.  69,  b,  c),  one  of  the  valves  of  the  shell  (the 
dorsal)  is  furnished  in  its  interior  with  a  pair  of  great  calca- 
reous spires,  which  served  for  the  support  of  the  long  and 
fringed  fleshy  processes  or  "  arms  "  which  were  attached  to  the 
sides  of  the  mouth.*  In  the  genus  Pentamerus  (fig.  70)  the 

*  In  all  the  Lamp-shells  the  mouth  is  provided  with  two  long  fleshy 
organs,    which  carry   delicate    filaments    on    their  sides,   and  which   are 

10 


Fig.  65. — Pterygotut  Anglicus, 
viewed  from  the  under  side,  reduced 
in  size,  and  restored,  c  c,  The  feelers 
(antennae),  terminating  in  nipping- 
claws  ;  o  o,  Eyes  ;  in  in,  Three  pairs  of 
jointed  limbs,  with  pointed  extremi- 
ties ;  n  n,  Swimming-paddles,  the  bases 
of  which  are  spiny  and  act  as  jaws. 
Upper  Silurian,  Lanarkshire.  (After 
Henry  Woodward.) 


126 


HISTORICAL   PALAEONTOLOGY. 


shell    is    curiously   subdivided    in   its   interior  by  calcareous 
plates.    The  Pentameri  commenced  their  existence  at  the  very 


Fig.  66. — Upper  Silurian  Polyzoa.  i,  Fan-shaped  frond  of  Rhinopora  verrncosa',  in, 
Portion  of  the  surface  of  the  same,  enlarged  ;  2  and  za,  Pfuenopora  ensiformis,  of  the 
natural  size  and  enlarged ;  3  and  jft,  Helopora  fragilis,  of  the  natural  size  and  en- 
larged ;  4  and  4*7,  Ptilodictya  raripora,  of  the  natural,  size  and  enlarged.  The  speci- 
mens are  all  from  the  Clinton  Formation  (May  Hill  Group)  of  Canada.  (Original.) 

close  of  the  Lower  Silurian  (Llandovery),  and  survived  to  the 
close  of  the  Upper  Silurian ;  but  they  are  specially  character- 
istic of  the  May  Hill  and  Wenlock  groups,  both  in  Britain 
and  in  other  regions.  One  species,  Pentamerus  galeatus,  is 
common  to  Sweden,  Britain,  and  America.  Amongst  the 
remaining  Upper  Silurian  Brachiopods  are  the  extraordinary 


usually  coiled  into  a  spiral.  These  organs  are  known  as  the  "arms," 
and  it  is  from  their  presence  that  the  name  of  "  Brachiopoda  "  is  derived 
(Gr.  brachion,  arm  ;  podes,  feet).  In  some  cases  the  arms  are  merely  coiled 
away  within  the  shell,  without  any  support ;  but  in  other  cases  they  are 
carried  upon  a  more  or  less  elaborate  shelly  loop,  often  spoken  of  as  the 
"carriage-spring  apparatus."  In  the  Spirifers,  and  in  other  ancient 
genera,  this  apparatus  is  coiled  up  into  a  complicated  spiral  (fig.  67).  It 


Fig.  67. — Spirifera  hysterica.     The  right-hand  figure  shows  the  interior  of  the 
dorsal  valve,  with  the  calcareous  spires  for  the  sup 


ipport   of  the  arms. 


is  these  "arms,"  with  or  without  the  supporting  loops  or  spires,  which 
serve  as  one  of  the  special  characters  distinguishing  the  Brachiopods  from 
the  true  Bivalves  (Lantdlibranchiatd). 


THE    UPPER   SILURIAN    PERIOD. 


127 


Trimerellids ;  the  old  and  at  the  same  time  modern  Lingulee, 
Distinct,  and  Cranicz ;  together  with  many  species  of  Atrypa 


Fig.  68.  —  Upper  Silurian  Brachiopods.  a  a',  Leptoccelia  plano-convexa,  Clinton 
Group,  America ;  b  b' ,  Rhynchonella  neglecta,  Clinton  Group,  America ;  c,  Rhynchonella 
cuneata,  Niagara  Group,  America,  and  Wenlock  Group,  Britain;  d  d',  Orthis  elegan- 
tnla,  Llandeilo  to  Ludlow,  America  and  Europe;  e  e,  Atrypa  hetnispJterica,  Clinton 
Group,  America,  and  Llandovery  and  May  Hill  Groups,  Britain  ;ff,  Atrypa  congesta, 
Clinton  Group,  America  ;  g g' ,  Orthis  Davidsoni,  Clinton  Group,  America.  (After  Hall, 
Billings,  and  the  Author.) 

(fig.  68,  e},  Leptoccelia  (fig.  68,  a],  Rhynchonella  (fig.  68,  b,  c\ 
Meristella  (fig.  69,  a,  <?,/),  Athyris,  Retzia,  Chonetes,  &c. 


Fig.  69. — <?,  a'  Meristella  intermedia,  Niagara  Group,  America ;  b,  Spirifera  Niagar- 
eiisis,  Niagara  Group,  America ;  c.  c ,  Spirifera  crispa,  May  Hill  to  Ludlow,  Britain,  and 
Niagara  Group,  America  ;  d,  Strophomena  (Streptorhynchus)  subplana,  Niagara  Group, 
America  ;  e,  Meristella  nai'iformis,  Niagara  Group,  America  ~,f,  Meristella  cylindrica, 
Niagara  Group,  America.  (After  Hall,  Billings,  and  the  Author.) 

The  higher  groups  of  the  Mollnsca  are  also  largely  repre- 
sented in  the  Upper  Silurian.  Apart  from  some  singular  types, 


128 


HISTORICAL   PAL/EONTOLOGY. 


such  as  the  huge  and  thick-shelled  Megalomi  of  the  American 
Wenlock  formation,  the  Bivalves  (Lamellibranchiata)  present 


Fig,  "jo.—Pentamenis  Knightii.      Wenlock  and  Ludlow.     The  right-hand 
figure  shows  the  internal  partitions  of  the  shell. 


little  of  special  interest;  for  though  sufficiently  numerous,  they 
are  rarely  well  preserved,  and  their  true  affinities  are  often  un- 
certain. Amongst  the  most  characteristic  genera  of  this  period 
may  be  mentioned  Cardiola  (fig.  71,  A  and  C)  and  Pterinea  (fig. 


Fig.  71. — Upper  Silurian  Bivalves.  A,  Cardioln  intemtpta,  Wenlock  and  Ludlow ; 
B,  Pterinea  subfalcata,  Wenlock ;  C,  Cardiola  fibrosa,  Ludlow.  (After  Salter  and 
M'Coy.) 

71,  B),  though  the  latter  survives  to  a  much  later  date.     The 
Univalves  (Gasteropoda)  are  very  numerous,  and  a  few  charac- 
teristic forms  are  here  figured  (fig.  72).     Of  these,  no  genus 
is  perhaps  more  characteristic  than  Euomphalus  (fig.  72,  b\ 
with  its  flat  discoidal  shell,  coiled  up  into  an  oblique  spiral, 
and  deeply  hollowed  out  on  one  side ;  but  examples  of  this 
group  are  both  of  older  and  of  more  modern  date.     Another 
very  extensive  genus,  especially  in  America,  is  Platyceras  (fig. 

72,  a  and/),  with  its  thin  fragile  shell — often  hardly  coiled  up 
at  all — its  minute  spire,  and  its  widely-expanded,  often  sinuated 
mouth.      The   British  Acroculia  should  probably  be  placed 
here,  and  the  group  has  with  reason  been  regarded  as  allied 
to  the  Violet-snails   (lanthina]  of  the   open   Atlantic.      The 


THE    UPPER   SILURIAN    PERIOD. 


129 


species  of  Platyostoma  (fig.  72,  ti)  also  belong  to  the  same 
family ;  and  the  entire  gtoup  is  continued  throughout  the 
Devonian  into  the  Carboniferous.  Amongst  other  well-known 
Upper  Silurian  Gasteropods  are  species  of  the  genera  Holopea 


h> 


Fig.  72.  —Upper  Silurian  Gasteropods.  a,  Platyceras  ventricosum,  Lower  Helder- 
berg,  America ;  b,  Euomphalies  discors,  Wenlock,  Britain ;  c ,  Holopella  obsoleta,  Lud- 
low,  Britain;  d,  Platyschisma  helicites,  Upper  Ludlow,  Britain  ;  e,  Holopella  grac  Hi  or, 
Wenlock,  Britain  ;f,  Platyceras  multisinuatum,  Lower  Helderberg,  America;  g,  Holo- 
pza  s-itbconica.  Lower  Helderberg,  America ;  h,  h' ',  Platyostoma  Niagarense,  Niagara 
Group,  America.  (After  Hall,  M'Coy,  and  Salter.) 

(fig.  72,  g),  Holopella  (fig.  72,  e),  Platyschisma  (fig.  72,  //), 
Cyclonema,  Pleurotomaria,  Murchisonia,  Trochomim,  &c.  The 
oceanic  Univalves  (Heteropods)  are  rep- 
resented mainly  by  species  of  Bellero- 
phon  ;  and  the  Winged  Snails,  or  Plero- 
pods,  can  still  boast  of  the  gigantic  Theccc 
and  Conularicz,  which  characterise  yet 
older  deposits.  The  commonest  genus 
of  Pteropoda,  however,  is  Tentaculites  (fig. 
73),  which  clearly  belongs  here,  though 
it  has  commonly  been  regarded  as  the 
tube  of  an  Ann  elide.  The  shell  in  this 
group  is  a  conical  tube,  usually  adorned 
with  prominent  transverse  rings,  and 
often  with  finer  transverse  or  longitudi- 
nal striae  as  well ;  and  many  beds  of  the 
IJpper  Silurian  exhibit  myriads  of  such  tubes  scattered  promis- 
cuously over  their  surfaces. 


*'ig  73-  —  Tentaculites  or- 
natu*.  Upper  Silurian  of 
Europe  and  North  America. 


130 


HISTORICAL   PALAEONTOLOGY. 


The  last  and  highest  group  of  the  Molhisca — that  of  the 
Cephalopoda  —  is  still  represented  only  by  Teirabranchiate 
forms ;  but  the  abundance  and  variety  of  these  is  almost 
beyond  belief.  Many  hundreds  of  different  species  are  known, 
chiefly  belonging  to  the  straight  Orthoceratites,  but  the  slightly- 
curved  Cyrtoceras  is  only  little  less  common.  There  are  also 
numerous  forms  of  the  genera  Phragmoceras,  Ascoceras,  Gyro- 
ceras,  Lituites,  and  Nautilus.  Here,  also,  are  the  first-known 
species  of  the  genus  Goniatites — a  group  which  attains  con- 
siderable importance  in  later  deposits,  and  which  is  to  be 
regarded  as  the  precursor  of  the  Ammonites  of  the  Secondary 
period. 

Finally,  we  find  ourselves  for  the  first  time  called  upon  to 
consider  the  remains  of  undoubted  vertebrate  animals,  in  the 
form  of  Fishes.     The  oldest  of  these  remains,  so  far  as  yet 
known,  are  found  in  the  Lower  Lucllow  rocks,  and  they  con- 
sist of  the  bony  head-shields  or  bucklers 
of  certain  singular  armoured  fishes  belong- 
ing to  the   group  of  the  Ganoids,  repre- 
sented  at   the  present  day  by  the  Stur- 
geons,  the   Gar-pikes   of  North  America, 
and  a  few  other  less  familiar  forms.     The 
principal  Upper  Silurian  genus  of  these  is 
Pteraspis,  and  the  annexed  illustration  (fig. 
74)  will  give  some  idea  of  the  extraordi- 
nary form  of  the  shield  covering  the  head 
in  these  ancient  fishes.     The  remarkable 
stratum  near  the  top  of  the  Ludlow  for- 
mation   known    as   the    "  bone-bed "   has 
also   yielded   the    remains    of    shark-like 
fishes.     Some  of  these,  for  which  the  name 
of   Onckus   has    been    proposed,    are    in   the   form    of  com- 
pressed, slightly- curved  spines  (fig.  75,  A),  which  would  appear 


Fig-  74- — Head-shield 
of  Pteraspis  Banksii, 
l.udlow  rocks.  (After 
Murchison.) 


Fig.  75- — A,  Spine  of  Onchus  tcnmstriafns  ;  B,  Shagreen-scales  of  Thelo&is. 
from  the  "  bone-bed  "  of  the  Upper  Ludlow  rocks.     (After  Murchison.) 


Both 


to  be  of  the  nature  of  the  strong  defensive  spines  implanted 
in  front  of  certain  of  the  fins  in  many  living  fishes.  Besides 
these,  have  been  found  fragments  of  prickly  skin  or  shagreen 
(Sphagodus],  along  with  minute  cushion-shaped  bodies  (Thdo- 


THE   UPPER   SILURIAN    PERIOD.  13! 

dus,  fig.  75,  B),  which  are  doubtless  the  bony  scales  of  some 
fish  resembling  the  modern  Dog-fishes.  As  the  above  mentioned 
remains  belong  to  two  distinct,  and  at  the  same  time  highly- 
organised,  groups  of  the  fishes,  it  is  hardly  likely  that  we  are 
really  presented  here  with  the  first  examples  of  this  great  class. 
On  the  contrary,  whether  the  so-called  "Conodonts"  should 
prove  to  be  the  teeth  of  fishes  or  not,  we  are  justified  in  ex- 
pecting that  unequivocal  remains  of  this  group  of  animals  will 
still  be  found  in  the  Lower  Silurian.  It  is  interesting,  also,  to 
note  that  the  first  appearance  of  fishes — the  lowest  class  of 
vertebrate  animals — so  far  as  known  to  us  at  present,  does  not 
take  place  until  after  all  the  great  sub-kingdoms  of  invertebrates 
have  been  long  in  existence ;  and  there  is  no  reason  for  think- 
ing that  future  discoveries  will  materially  affect  the  relative 
order  of  succession  thus  indicated. 


LITERATURE. 

From  the  vast  and  daily-increasing  mass  of  Silurian  literature,  it  is  im- 
possible to  do  more  than  select  a  small  number  of  works  which  have  a 
classical  and  historical  interest  to  the  English-speaking  geologist,  or  which 
embody  researches  on  special  groups  of  Silurian  animals — anything  like  an 
enumeration  of  all  the  works  and  papers  on  this  subject  being  wholly  out 
of  the  question.  Apart,  therefore,  from  numerous  and  in  many  cases 
extremely  important  memoirs,  by  various  well-known  observers,  both  at 
home  and  abroad,  the  following  are  some  of  the  more  weighty  works  to 
which  the  student  may  refer  in  investigating  the  physical  characters  and 
succession  of  the  Silurian  strata  and  their  fossil  contents  : — 

(1)  'Siluria.'     Sir  Roderick  Murchison. 

(2)  '  Geology  of  Russia  in  Europe.'     Murchison  (with  M.  de  Verneuil 

and  Count  von  Keyserling). 
"(3)   '  Bassiu  Silurian  de  Boheme  Centrale.'     Barrande. 

(4)  '  Introduction  to  the  Catalogue  of  British  Palaeozoic  ^Fossils  in  the 

Woodwardian  Museum  of  Cambridge.'     Sedgwick. 

(5)  <  Die  Urwelt  Russlands.'     Eichwald. 

(6)  '  Report  on  the  Geology  of  Londonderry,  Tyrone,'  &c.      Portlock. 

(7)  "Geology  of  North  Wales" — 'Mem.  Geol.  Survey  of  Great  Britain,' 

vol.  iii.     Ramsay.  • 

(8)  *  Geology  of  Canada,'  1863,  Sir  W.  E.  Logan  ;  and  the  *  Reports  of 

Progress  of  the  Geological  Survey'  since  1863. 

(9)  '  Memoirs  of  the  Geological  Survey  of  Great  Britain.' 

(10)  '  Reports  of  the  Geological   Surveys  of  the  States  of  New  York, 

Illinois,  Ohio,  Iowa,  Michigan,  Vermont,  Wisconsin,  Minne- 
sota,' &c.  Bv  Emmons,  Hall,  Worthen,  Meek,  Newberry, 
Orton,  Winchell,  Dale  Owen,  &c. 

(11)  'Thesaurus  Siluricus.'     Bigsby. 

(12)  'British  Paleozoic  Fossils.'     M'Coy. 

(13)  '  Synopsis  of  the  Silurian  Fossils  of  Ireland,'     M'Coy. 

(14)  "  Appendix  to  the  Geology  of  North  Wales  " — '  Mem.  Geol.  Survey,' 

vol.  iii.     Salter. 


132  HISTORICAL  PALEONTOLOGY. 

(15)  '  Catalogue  of  the  Cambrian  and  Silurian  Fossils  in  the  Woodward  - 

ian  Museum  of  Cambridge. '     Salter. 

(16)  '  Characteristic  British  Fossils.'     Baily. 

(17)  *  Catalogue  of  British  Fossils.'     Morris. 

(18)  '  Palaeozoic  Fossils  of  Canada.'     Billings. 

(19)  'Decades  of  the  Geological  Survey  of  Canada.'     Billings,  Salter, 

Rupert  Jones. 

(20)  '  Decades  of  the  Geological  Survey  of  Great  Britain.'    Salter,  Edward 

Forbes. 

(21)  '  Palaeontology  of  New  York,'  vols.  i.-iii.     Hall. 

(22)  '  Palaeontology  of  Illinois.'     Meek  and  Worthen. 

(23)  '  Palaeontology  of  Ohio.'     Meek,  Hall,  Whitfield,  Nicholson. 

(24)  'Silurian  Fauna  of  West  Tennessee'  (Silurische  Fauna  des  West- 

lichen  Tennessee).     Ferdinand  Rcemer. 

(25)  '  Reports  on  the  State  Cabinet  of  New  York.'     Hall. 

(26)  '  Lethaea  Geognostica.'     Bronn. 

(27)  '  Index  Palaeontologicus.'     Bronn. 
(25)   '  Lethaa  Rossica.'     Eichwald. 

(29)  '  Lethaea  Suecica.'     Hisinger. 

(30)  '  Palaeontologica  Suecica.'     Angelin. 

(31)  *  Petrefacta  Germaniae.'     Goldfuss. 

(32)  '  Versteinerungen  der  Grauwacken- Formation  in  Sachsen.'    Geinitz. 

(33)  '  Organisation  of  Trilobites '  (Ray  Society).      Burmeister. 

(34)  'Monograph  of  the  British  Trilobites'  (Palaeontographical  Society). 

Salter. 

(35)  '  Monograph  of  the  BritishMerostomata'  (Palaeontographical  Society). 

Henry  Woodward. 

(36)  '  Monograph  of  British  Brachiopoda '  (Palaeontographical  Society). 

Thomas  Davidson. 

(37)  '  Graptolites  of  the  Quebec  Group.'    James  Hall. 

(38)  '  Monograph  of  the  British  Graptolitidae.'     Nicholson. 

(39)  '  Monographs  on  the  Trilobites,   Pteropods,   Cephalopods,  Grapto- 

lites,' &c.     Extracted  from  the  '  Systeme  Silurien  du  Centre  de 
la  Boheme. '     Barrande. 

(40)  '  Polypiers  Fossiles  des  Terrains  Paleozoiques,'  and  'Monograph  of 

the  British  Corals'    (Palaeontographical  Society).      Milne   Ed- 
wards and  Jules  Haime. 


CHAPTER    XL 

THE  DEVONIAN  AND   OLD  RED  SANDSTONE 
PERIOD. 

Between  the  summit  of  the  Ludlow  formation  and  the  strata 
which  are  universally  admitted  to  belong  to  the  Carboniferous 


DEVONIAN   AND   OLD    RED    PERIOD.  133 

series  is  a  great  system  of  deposits,  to  which  the  name  of  "  Old 
Red  Sandstone"  was  originally  applied,  to  distinguish  them 
from  certain  arenaceous  strata  which  lie  above  the  coal  ("  New 
Red  Sandstone").  The  Old  Red  Sandstone,  properly  so 
called,  was  originally  described  and  investigated  as  occurring 
in  Scotland  and  in  South  Wales  and  its  borders ;  and  similar 
strata  occur  in  the  south  of  Ireland.  Subsequently  it  was 
discovered  that  sediments  of  a  different  mineral  nature,  and 
containing  different  organic  remains,  intervened  between  the 
Silurian  and  the  Carboniferous  rocks  on  the  continent  of  Eu- 
rope, and  strata  with  similar  palaeontological  characters  to  these 
were  found  occupying  a  considerable  area  in  Devonshire.  The 
name  of  "  Devonian  "  was  applied  to  these  deposits ;  and  this 
title,  by  common  usage,  has  come  to  be  regarded  as  synony- 
mous with  the  name  of  "  Old  Red  Sandstone."  Lastly,  a 
magnificent  series  of  deposits,  containing  marine  fossils,  and 
undoubtedly  equivalent  to  the  true  "Devonian"  of  Devon- 
shire, Rhenish  Prussia,  Belgium,  and  France,  is  found  to  inter- 
vene in  North  America  between  the  summit  of  the  Silurian 
and  the  base  of  the  Carboniferous  rocks. 

Much  difficulty  has  been  felt  in  correlating  the  true  "  Devon- 
ian Rocks"  with  the  typical  "  Old  Red  Sandstone" — this  diffi- 
culty arising  from  the  fact  that  though  both  formations  are 
fossiliferous,  the  peculiar  fossils  of  each  have  only  been  rarely 
and  partially  found  associated  together.  ,  The  characteristic 
crustaceans  and  many  of  the  characteristic  fishes  of  the  Old 
Red  are  wanting  in  the  Devonian ;  whilst  the  corals  and 
marine  shells  of  the  latter  do  not  occur  in  the  former.  It  is 
impossible  here  to  enter  into  any  discussion  as  to  the  merits 
of  the  controversy  to  which  this  difficulty  has  given  origin. 
No  one,  however,  can  doubt  the  importance  and  reality  of  the 
Devonian  series  as  an  independent  system  of  rocks  to  be  in- 
tercalated in  point  of  time  between  the  Silurian  and  the  Car- 
boniferous. The  want  of  agreement,  both  lithologically  and 
palaeontologically,  between  the  Devonian  and  the  Old  Red, 
can  be  explained  by  supposing  that  these  two  formations, 
though  wholly  or  in  great  part  contemporaneous,  and  therefore 
strict  equivalents,  represent  deposits  in  two  different  geographi- 
cal areas,  laid  down  under  different  conditions.  On  this  view, 
the  typical  Devonian  rocks  of  Europe,  Britain,  and  North 
America  are  the  deep-sea  deposits  of  the  Devonian  period,  or, 
at  any  rate,  are  genuine  marine  sediments  formed  far  from 
land.  On  the  other  hand,  the  "  Old  Red  Sandstone "  of 
Britain  and  the  corresponding  "Gaspe  Group"  of  Eastern 


134  HISTORICAL  PALEONTOLOGY. 

Canada  represent  the  shallow-water  shore-deposits  of  the  same 
period.  In  fact,  the  former  of  these  last -mentioned  de- 
posits contains  no  fossils  which  can  be  asserted  positively 
to  be  marine  (unless  the  Eurypterids  be  considered  so) ;  and 
it  is  even  conceivable  that  it  represents  the  sediments  of  an 
inland  sea.  Accepting  this  explanation  in  the  meanwhile, 
we  may  very  briefly  consider  the  general  succession  of  the 
deposits  of  this  period  in  Scotland,  in  Devonshire,  and  in 
North  America. 

In  Scotland  the  "  Old  Red  "  forms  a  great  series  of  arena- 
ceous and  conglomeratic  strata,  attaining  a  thickness  of  man}' 
thousands  of  feet,  and  divisible  into  three  groups.  Of  these, 
the  Lower  Old  Red  Sandstone  reposes  with  perfect  conform- 
ity upon  the  highest  beds  of  the  Upper  Silurian,  the  two  for- 
mations being  almost  inseparably  united  by  an  intermediate 
series  of  "passage-beds."  In  mineral  nature  this  group  con- 
sists principally  of  massive  conglomerates,  sandstones,  shales, 
and  concretionary  limestones  ;  and  its  fossils  consist  chiefly  of 
large  crustaceans  belonging  to  the  family  of  the  Ewypterids, 
fishes,  and  plants.  The  Middle  Old  Red  Sandstone  consists  of 
flagstones,  bituminous  shales,  and  conglomerates,  sometimes 
with  irregular  calcareous  bands  ;  and  its  fossils  are  principally 
fishes  and  plants.  It  may  be  wholly  wanting,  when  the  Upper 
Old  Red  seems  to  repose  unconformably  upon  the  lower  divi- 
sion of  the  series.  The  Upper  Old  Red  Sandstone  consists  of 
conglomerates  and  grits,  along  with  a  great  series  of  red  and 
yellow  sandstones — the  fossils,  as  before,  being  fishes  and  re- 
mains of  plants.  The  Upper  Old  Red  graduates  upwards 
conformably  into  the  Carboniferous  series. 

The  Devonian  rocks  of  Devonshire  are  likewise  divisible 
into  a  lower,  middle,  and  upper  division.  The  Lower 
Devonian  or  Lynton  Gronp  consists  of  red  and  purple  sand- 
stones, with  marine  fossils,  corresponding  to  the  "Spirifer 
Sandstein  "  of  Germany,  and  to  the  arenaceous  deposits  (Scho- 
harie  and  Cauda-Galli  Grits)  at  the  base  of  the  American 
Devonian.  The  Middle  Devoiiian  or  Ilfracombe  Group  consists 
of  sandstones  and  flags,  with  calcareous  slates  and  crystalline 
limestones,  containing  many  corals.  It  corresponds  with  the 
great  "  Eifel  Limestone  "  of  the  Continent,  and,  in  a  general 
way,  with  the  Corniferous  Limestone  and  Hamilton  group  of 
North  America.  The  Upper  Devonian  or  Pilton  Group,  lastly, 
consists  of  sandstones  and  calcareous  shales  which  correspond 
with  the"Clymenia  Limestone"  and  "  Cypridina  Shales  "of 
the  Continent,  and  with  the  Chemimg  and  Portage  groups  of 


DEVONIAN    AND   OLD    RED    PERIOD.  135 

North  America.  It  seems  quite  possible,  also,  that  the  so- 
called  "  Carboniferous  Slates "  of  Ireland  correspond  with 
this  group,  and  that  the  former  would  be  more  properly  re- 
garded as  forming  the  summit  of  the  Devonian  than  the 
base  of  the  Carboniferous. 

In  no  country  in  the  world,  probably,  is  there  a  finer 
or  more  complete  exposition  of  the  strata  intervening  be- 
tween the  Silurian  and  Carboniferous  deposits  than  in  the 
United  States.  The  following  are  the  main  subdivisions 
of  the  Devonian  rocks  in  the  State  of  New  York,  where 
the  series  may  be  regarded  as  being  typically  developed 
(fig.  67):- 

(1)  Cauda-Galh  Grit  and  Schohane  Grit. — Considering  the 
"  Orfskany  Sandstone  "  as  the  summit  of  the  Upper  Silurian, 
the  base  of  the  Devonian  is  constituted  by  the  arenaceous 
deposits  known  by  the  above  names,  which  rest  quite  conform- 
ably  upon    the    Silurian,    and   which    represent    the    Lower 
Devonian  of  Devonshire.     The  Cauda-Galli  Grit  is  so  called 
from  the  abundance  of  a  peculiar   spiral  fossil   (Spirophyton 
cauda-Gatti},  which  is  of  common  occurrence  in  the  Carbon- 
iferous rocks  of  Britain,  and  is  supposed  to  be  the  remains 
of  a  sea-weed. 

(2)  The    Corniferous  or    Upper  Helderberg  Limestone.  —  A 
series  of  limestones  usually  charged  with  considerable  quan- 
tities of  siliceous  matter  in  the  shape 'of  hornstone  or  chert 
(Lat.  cornu,  horn).     The  thickness  of  this  group  rarely  exceeds 
300  feet ;  but  it  is  replete  with  fossils,  more  especially  with 
the  remains  of  corals.      The  Corniferous    Limestone    is    the 
equivalent  of  the  coral-bearing  limestones  of  the  Middle  De- 
vonian of  Devonshire  and   the  great   "  Eifel  Limestone "   of 
Germany. 

(3)  The  Hamilton   Group — consisting  of  shales  at  the  base 
("  Marcellus   shales ") ;  flags,   shales,   and  impure  limestones 
("Hamilton  beds")  in  the  middle ;  and  again  a  series  of  shales 
("Genesee  Slates")  at  the  top.     The  thickness  of  this  group 
varies  from   200  to   1200  feet,  and  it  is  richly  charged  with 
marine  fossils. 

(4)  The  Portage  Groiip. — A  great  series  of  shales,  flags,  and 
shaly  sandstones,  with  few  fossils. 

(5)  The  Chemung  Group. — Another  great    series   of  sand- 
stones and  shales,  but  with  many  fossils.     The  Portage  and 
Chemung  groups  may  be  regarded  as  corresponding  with  the 
Upper    Devonian   of  Devonshire.     The    Chemung  beds    are 
succeeded  by  a  great  series  of  red  sandstones  and  shales — the 


136  HISTORICAL   PAL/EONTOLOGY. 

"  Catskill  Group" — which  pass  conformably  upwards  into  the 
Carboniferous,  and  which  may  perhaps  be  regarded  as  the 
equivalent  of  the  great  sandstones  of  the  Upper  Old  Red  in 
Scotland. 

Throughout  the  entire  series  of  Devonian  deposits  in  North 
America  no  unconformability  or  physical  break  of  any  kind 
has  hitherto  been  detected  ;  nor  is  there  any  marked  interrup- 
tion to  the  current  of  life,  though  each  subdivision  of  the  series 
has  its  own  fossils.  No  completely  natural  line  can  thus  be 
indicated,  dividing  the  Devonian  in  this  region  from  the  Silu- 
rian on  the  one  hand,  and  the  Carboniferous  on  the  other 
hand.  At  the  same  time,  there  is  the  most  ample  evidence, 
both  stratigraphical  and  palaeontological,  as  to  the  complete 
independence  of  the  American  Devonian  series  as  a  distinct 
life-system  between  the  older  Silurian  and  the  later  Carbon- 
iferous. The  subjoined  section  (fig.  76)  shows  diagrammati- 
cally  the  general  succession  of  the  Devonian  rocks  of  North 
America. 

As  regards  the  life  of  the  Devonian  period,  we  are  now 
acquainted  with  a  large  and  abundant  terrestrial  flora — this 
being  the  first  time  that  we  have  met  with  a  land  vegetation 
capable  of  reconstruction  in  any  fulness.  By  the  researches 
of  Goeppert,  Unger,  Dawson,  Carruthers,  and  other  botanists, 
a  knowledge  has  been  acquired  of  a  large  number  of  Devonian 
plants,  only  a  few  of  which  can  be  noticed  here.  As  might 
have  been  anticipated,  the  greater  number  of  the  vegetable 
remains  of  this  period  have  been  obtained  from  such  shallow- 
water  deposits  as  the  Old  Red  Sandstone  proper  and  the  Gaspe 
series  of  North  America,  and  few  traces  of  plant  life  occur  in 
the  strictly  marine  sediments.  Apart  from  numerous  remains, 
mostly  of  a  problematical  nature,  referred  to  the  comprehensive 
group  of  the  Sea-weeds,  a  large  number  of  Ferns  have  now 
been  recognised,  some  being  of  the  ordinary  plant-like  type 
(PecopteriS)  Neuropteris,  Alethopteris,  Sphenopteris,  &c.),  whilst 
others  belong  to  the  gigantic  group  of  the  "  Tree  -  ferns " 
(Psaronius,  Caulopteris,  &c.)  Besides  these  .there  is  an  abun- 
dant development  of  the  singular  extinct  types  of  the  Lepido- 
dendroids,  the  Sigillarioids,  and  the  Calamitcs,  all  of  which 
attained  their  maximum  in  the  Carboniferous.  Of  these,  the 
Lepidodendra  may  be  regarded  as  gigantic,  tree-like  Club-mosses 
(Lyccpodiacea) ;  the  Calamites  are  equally  gigantic  Horse-tails 
(Equisetacecz] ;  and  the  Sigillarioids,  equally  huge  in  size,  in 
some  respects  hold  a  position  intermediate  between  the  Club- 
mosses  and  the  Pines  (Conifers).  The  Devonian  rocks  have 


DEVONIAN    AND   OLD   RED   PERIOD. 


137 


GENERALISED  SECTION  OF  THE  DEVONIAN  ROCKS  OF 
NORTH  AMERICA. 

Fig.  76- 


Catskill  Group. 


Chemung  Group. 
Portage  Group. 

Hamilton  Group. 


Corniferous  Limestone. 


Schoharie  Grit. 
Cauda-Galli  Grit. 
Oriskany  Sandstone. 


Lower  Heldeiberg. 


also  yielded  traces  of  many  other  plants  (such  as  Annular ia, 
Asterophyllites,  Cardiocarpon,  &c.),  which  acquire  a  greater  pre- 
dominance in  the  Carboniferous  period,  and  which  will  be 
spoken  of  in  discussing  the  structure  of  the  plants  of  the  Coal- 
measures.  Upon  the  whole,  the  one  plant  which  may  be  con- 
sidered as  specially  characteristic  of  the  Devonian  (though  not 
confined  to  this  series)  is  the  Psilophyton  (fig.  77)  of  Dr  Daw- 
son.  These  singular  plants  have  slender  branching  stems, 
with  sparse  needle-shaped  leaves,  the  young  stems  being  at 
first  coiled  up,  crosier-fashion,  like  the  young  fronds  of  ferns, 
whilst  the  old  branches  carry  numerous  spore-cases.  The 


138 


HISTORICAL   PALEONTOLOGY. 


stems  and  branches  seem  to  have  attained  a  height  of  two  or 
three  feet ;  and  they  sprang  from  prostrate  "  root-stocks  "  or 

creeping  stems.  Upon  the  whole, 
Principal  Davvson  is  disposed  to 
regard  Psilophyton  as  a  "general- 
ised type"  of  plants  intermediate 
between  the  Ferns  and  the  Club- 
mosses.  Lastly,  the  Devonian  de- 
posits have  yielded  the  remains  of 
the  first  actual  trees  with  which  we 
are  as  yet  acquainted.  About  the 
nature  of  some  of  these  (Ormoxylon 
and  Dadoxylon)  no  doubt  can  be 
entertained,  since  their  trunks  not 
only  show  the  concentric  rings  of 
growth  characteristic  of  exogen- 
ous trees  in  general,  but  their 
woody  tissue  exhibits  under  the 
microscope  the  "  discs  "  which  are 
characteristic  of  the  wood  of  the 
Pines  and  Firs  (see  fig.  2).  The 
singular  genus  Prototaxites,  how- 
ever, which  occurs  in  an  older  por- 
tion of  the  Devonian  series  than 
the  above,  is  not  in  an  absolutely 
unchallenged  position.  By  Prin- 
cipal Dawson  it  is  regarded  as  the 
trunk  of  an  ancient  Conifer — the 
most  ancient  known  ;  but  Mr 
Carruthers  regards  it  as  more  pro- 
bably the  stem  of  a  gigantic  sea- 
weed. The  trunks  of  Prototaxites 
(fig.  78,  A)  vary  from  one  to  three 
feet  in  diameter,  and  exhibit  con- 
centric rings  of  growth  ;  but  its 
woody  fibres  have  not  hitherto 
been  clearly  demonstrated  to  pos- 
sess clipcs.  Before  leaving  the 

Devonian  vegetation,  it  may  be  mentioned  that  the  hornstone 
or  chert  so  abundant  in  the  Corniferous  limestone  of  North 
America  has  been  shown  to  contain  the  remains  of  various 
microscopic  plants  {Diatoms  and  Desmids).  We  find  also  in 
the  same  siliceous  material  the  singular  spherical  bodies,  with 
radiating  spines,  which  occur  so  abundantly  in  the  chalk  flints, 
and  which  are  termed  Xanthidia.  These  may  be  regarded 


*^g-    77  — Restoration   of  Psilo- 
phyton  firinceps      Devonian,   Can 
.fter  Da' 


ada.     (Afte 


iwson.) 


DEVONIAN   AND   OLD   RED   PERIOD. 


139 


as  probably  the  spore-cases  of  the  minute  plants  known  as 
Desmiditz. 


Fig.  78. — A,  Trunk  of  Prototaxites  Logani,  eighteen  inches  in  diameter,  as  seen  in  the 
cliff  near  L'Anse  Brehaut,  Gaspe  ;  B,  Two  wood-cells  showing  spiral  fibres  and  obscure 
pores,  highly  magnified.  Lower  Devonian,  Canada.  (After  Dawson.) 

The  Devonian  Protozoans  have  still  to  be  fully  investigat- 
ed. True  Sponges  (such  as  Astrceospongia,  Sphcerospongia, 
&c.)  are  not  unknown;  but  by  far  the  commonest  repre- 
sentatives of  this  sub -kingdom  in  the  Devonian  strata  are 
Stromatopora  and  its  allies.  These  singular  organisms  (fig. 
79)  are  not  only  very  abundant  in  some  of  the  Devonian  lime- 
stones— both  in  the  Old  World  and  the  New — but  they  often 
attain  very  large  dimensions.  However  much  they  may  differ 
in  minor  details,  the  general  structure  of  these  bodies  is  that 
of  numerous,  concentrically-arranged,  thin,  calcareous  laminae, 
separated  by  narrow  interspaces,  which  in  turn  are  crossed  by 
numerous  delicate  vertical  pillars,  giving  the  whole  mass  a 
cellular  structure,  and  dividing  it  into  innumerable  minute 
quadrangular  compartments.  Many  of  the  Devonian  Stromato- 
porce  also  exhibit  on  their  surface  the  rounded  openings  of 
canals,  which  can  hardly  have  served  any  other  purpose  than 
that  of  permitting  the  sea-water  to  gain  ready  access  to  every 
part  of  the  organism. 

No  true  Graptolites  have  ever  been  detected  in  strata  of 


140 


HISTORICAL   PAL.  1- ONTOLOGY. 


Devonian  age ;  and  the  whole  of  this  group  has  become  ex- 
tinguished— unless  we  refer  here  the  still  surviving  Dictyonemte. 


Fig.  79. — a,  Part  of  the  under  surface  of  Stromatopora  tulerculata,  showing  the 
wrinkled  basement  membrane  and  the  openings  of  water-canals,  of  the  natural  size;  b, 
Portion  of  the  upper  surface  of  the  same,  enlarged  ;  c,  Vertical  section  of  a  fragment,  mag- 
nified to  show  the  internal  structure.  Corniferous  Limestone,  Canada.  (Original.) 

The  Cce tenter ates,  however,  are  represented  by  a  vast  number 
of  Corals,  of  beautiful  forms  and  very  varied  types.  The 
marbles  of  Devonshire,  the  Devonian  limestones  of  the  Eifel 
and  of  France,  and  the  calcareous  strata  of  the  Corniferous 
and  Hamilton  groups  of  America,  are  often  replete  with  the 
skeletons  of  these  organisms — so  much  so  as  to  sometimes 
entitle  the  rock  to  be  considered  as  representing  an  ancient 
coral-reef.  In  some  instances  the  Corals  have  preserved  their 
primitive  calcareous  composition  ;  and  if  they  are  embedded 
in  soft  shales,  they  may  weather  out  of  the  rock  in  almost  all 
their  original  perfection.  In  other  cases,  as  in  the  marbles  of 
Devonshire,  the  matrix  is  so  compact  and  crystalline  that  the 
included  corals  can  only  be  satisfactorily  studied  by  means  of 
polished  sections.  In  other  cases,  again,  the  corals  have  been 
more  or  less  completely  converted  into  flint,  as  in  the  Cornifer- 
ous limestone  of  North  America.  When  this  is  the  case,  they 
often  come,  by  the  action  of  the  weather,  to  stand  out  from 


DEVONIAN    AND    OLD    RED    PERIOD. 


the  enclosing  rock  in  the  boldest  relief,  exhibiting  to  the  ob- 
server the  most  minute  details  of  their  organisation.    As  before, 


Fig.  8 1. — Zaphrentis  cornicn7a,  of  the 
natural  size.  Devonian,  America.  (Ori- 
ginal.) 


Fig.  So.  —  Cystiphyllnm  7>esiculosnvi, 
showing  a  succession  of  cups  produced  by 
budding  from  the  original  coral.  Of  the 
natural  size.  Devonian,  America  and 
Europe.  (Original.) 


Fig.  82. — Heliophylhtm  exigiium,  view- 
ed from  in  front  and  behind.  Of  the  natu- 
ral size.  Devonian,  Canada.  (Original.) 


the  principal  representatives  of  the  Corals  are  still  referable  to 
the' groups  of  the  Rugosa  and  Tabulata.  Amongst  the  Rugose 
group  we  find  a  vast  number  of  simple  "  cup-corals,"  generally 
known  by  the  quarrymen  as  "  horns,"  from  their  shape.  Of 
11 


142  HISTORICAL    PALAEONTOLOGY. 

the  many  forms  of  these,  the  species  of  Cyathophylliim,  Helio- 
phyllum  (fig.  82),  Zaphrentis  (fig.  81),  and  Cystiphyllum  (fig.  80), 
are  perhaps  those  most  abundantly  represented — none  of  these 
genera,  however,  except  Heliophyllum,  being  peculiar  to  the 
Devonian  period.  There  are  also  numerous  compound  Ru- 
gose corals,  such  as  species  of  EridophyUum^  Diphyphyl- 
lum,  Syringopora,  Phillipsastrcea,  and  some  of  the  forms  of 
Cyathophyllum  and  Crepidophyllum  (fig.  83).  Some  of  these 
compound  corals. attain  a  very  large  size,  and  form  of  thera- 


Fig.  83. — Portion  of  a  mass  of  Crepidophyllum  Archinci,  of  the  natural  size. 
Hamilton  *  ormation,  Canada.     (After  Billings.) 

selves  regular  beds,  which  have  an  analogy,  at  any  rate,  with 
existing  coral-reefs,  though  there  are  grounds  for  believing  that 
these  ancient  types  differed  from  the  modern  reef-builders  in 
being  inhabitants  of  deep  water.  The  "  Tabulate  Corals  "  are 
hardly  less  abundant  in  the  Devonian  rocks  than  the  Rugosa  ; 
and  being  invariably  compound,  they  hardly  yield  to  the  latter 
in  the  dimensions  of  the  aggregations  which  they  sometimes 
form. 

The  commonest,  and  at  the  same  time  the  largest,  of  these 
are  the  "  honeycomb  corals,"  forming  the  genus  Favosites 
(figs.  84,  -85),  which  derive  both  their  vernacular  and  their 
technical  names  from  their  great  likeness  to  masses  of  petrified 
honeycomb.  The  most  abundant  species  are  Favosites  Goth- 
landica  and  F.  hemispheric^  both  here  figured,  which  form 
masses  sometimes  not  less  than  two  or  three  feet  in  diameter. 
Whilst  Favosites  has  acquired  a  popular  name  by  its  honey- 
combed appearance,  the  resemblance  of  Michelinia  to  a  fossil- 


DEVONIAN    AND    OLD    RED    PERIOD.  143 

ised  wasp's  nest  with  the  comb  exposed  is  hardly  less  strik- 
ing, and   has   earned  for  it   a   similar   recognition   from  the 


Fig.  84. — Portion  of  a  mass  of  Favo-  Fig.  85. — Fragment  of  Favcsiteshemi- 

sites  Gothlandica,   of  the  natural    size.  spherica,  of  the  natural  size.  Upper  Silu- 

Upper  Silurian  and  Devonian  of  Europe  rian  and  Devonian  of  America.    '(After 

and  America.     (Original.)  Billings.) 

non-scientific  public.  In  addition  to  these,  there  are  numer- 
ous branching  or  plant-like  Tabulate  Corals,  often  of  the  most 
graceful  form,  which  are  distinctive  of  the  Devonian  in  all 
parts  of  the  world. 

The  Echinoderms  of  the  Devonian  period  call  for  little 
special  notice.  Many  of  the  Devonian  limestones  are  "crin- 
oidal;"  and  the  Crinoids  are  the  most  abundant  and  widely- 
distributed  representatives  of  their  class  in  the  deposits  of 
this  period.  . 

The  Cystideans,  with  doubtful  exceptions,  have  not  been 
recognised  in  the  Devonian ;  and  their  place  is  taken  by  the 
allied  group  of  the  "  Pentremites/'  which  will  be  further  spoken 
of  as  occurring  in  the  Carboniferous  rocks.  On  the  other  hand, 
the  Star-fishes,  Brittle-stars,  and  Sea-urchins  are  all  continued 
by  types  more  or  less  closely  allied  to  those  of  the  preceding 
Upper  Silurian. 

Of  the  remains  of  Ringed-worms  (Anneltdes),  the  most  numer- 
ous and  the  most  interesting  are  the  calcareous  envelopes  of 
some  small  tube-inhabiting  species.  No  one  who  has  visited 
the  seaside  can  have  failed  to  notice  the  little  spiral  tubes  of 
the  existing  Spirorbis  growing  attached  to  shells,  or  covering 
the  fronds  of  the  commoner  Sea- weeds  (especially  Fucus  ser- 
ratus).  These  tubes  are  inhabited  by  a  small  Annelide,  and 
structures  of  a  similar  character  occur  not  uncommonly  from 
the  Upper  Silurian  upwards.  In  the  Devonian  rocks,  Spir- 
orbis is  an  extremely  common  fossil,  growing  in  hundreds 
attached  to  the  outer  surface  of  corals  and  shells,  and  appearing 


144 


HISTORICAL   PALEONTOLOGY. 


in  many  specific  forms  (figs.  86  and  87) ;  but  almost  all  the 
known  examples  are  of  small  size,  ar.d  are  liable  to  escape  a 

cursory  examination. 

The  Crustaceans  of 
the  Devonian  are  prin- 
c i  pal  I  y  Eurypterids  and 
Trilobites.  Some  of  the 
former  attain  gigantic 
dimensions,  and  the 

Fig.  87.—  a,  Sfiirorbis  ovtfihalodes,  natural  size         qimrrvmen  intlieScOtcll 
and    enlarged,  Devonian,   Europe   and    America  ;          Ai  j   T»      j       •          ,1  ,1 

b,  Spircrbis  Arkonensis,  of  the  natural  size   and          U«*   r^O.  glVC   them  the 
enlarged  ;  c,  The  same,  with  the  tube  twisted  in 
the  reverse  direction.     Devonian,  America,    (Ori- 
Cinal.) 


name  of  "  seraphim/' 
from  their  singular 
scale  -  like  ornamenta- 
tion. The  Trilobites, 
though  still  sufficiently 
abundant  in  some  local- 
ities, have  undergone  a 
yet  further  diminution 
since  the  close  of  the 
Upper  Silurian.  In  both 
America  and  Europe 
quite  a  number  of  gen- 
eric types  have  survived  from  the  Silurian,  but  few  or  no  new 
ones  make  their  appearance  during  this  period  in  either  the  Old 


Fig.  88. — a  b,  Spirorbis  laxns,  enlarged,  Upper 
Silurian,  America;  c,  Spirorbis  spinnlijera,  of  the 
natural  size  and  enlarged,  Devonian,  Canada.  (Af- 
ter Hall  and  the  Author.) 


Fig.  88. — Devonian  Trilobites  n,  Phaeops  lat!/rons,'Dzvo-n\a.n  of  Britain,  the  Conti- 
nent of  Europe,  and  South  America  ;  b,  Homalonotus  armatns,  Europe  ;  c,  Phacops 
(Trimerocephalns)  Icevis,  Europe;  d,  Head-shield  of  Phacops  (f'ortlockia)  granulatns, 
Europe.  (After  Salter  and  Burmeister.) 

World  or  the  New.     The  species,  however,  are  distinct ;  and  the 


DEVONIAN   AND   OLD   RED    PERIOD. 


principal  forms  belong  to  the  genera  Phacops  (fig.  88,  a,  c,  d\ 
Homalonotus  (fig.  88,  b\  Proetus,  and  Bronteus.  The  species 
figured  above  under  the  name  of  Phacops  latifrons  (fig.  88,  a), 
has  an  almost  world-wide  distribution,  being  found  in  the 
Devonian  of  Britain,  Belgium,  France,  Germany,  Russia,  Spain, 
and  South  America  ;  whilst  its  place  is  taken  in  North  Ame- 
rica by  the  closely-allied  Phacops  rana.  In  addition  to  the 
Trilobites,  the  Devonian  deposits  have  yielded  the  remains  of 
a  number  of  the  minute  Ostracoda,  such  as  Entomis  ("  Cypri- 
dina"),  Leper ditia,  £c.,  which  sometimes  occur  in  vast  num- 
bers, as  in  the  so-called  "  Cypridina  Slates  "  of  the  German 
Devonian.  There  are  also  a  few  forms  of  Phyllopods  (Es- 
theria).  Taken  as  a  whole,  the  Crustacean  fauna  of  the 
Devonian  period  presents  many  alliances  with  that  of  the 
Upper  Silurian,  but  has  only  slight  relationships  with  that  of 
the  Lower  Carboniferous. 

Besides  Crustaceans,  we  meet  here  for  the  first  time  with 
the  remains  of  ah  '-breathing  Articulates,  in  the  shape  of  Insects. 
So  far,  these  have  only  been  obtained  from  the  Devonian 
rocks  of  North  America,  and  they  indicate  the  existence  of  at 
least  four  generic  types,  all  more  or  less  allied  to  the  existing 
May-flies  (Ephemeridce}.  One  of  these  interesting  primitive 
insects,  namely,  Platephemera  aiitiqiia  (fig.  89),  appears  to  have 
measured  five  inches  in  ex- 
panse of  wing  ;  and  another 
(Xenoneura  antiqiioruui)  has 
attached  to  its  wing  the  re- 
mains of  a  "  stridulating- 
organ  "  similar  to  that  pos- 
sessed by  the  modern  Grass- 
hoppers— the  instrument,  as 
Principal  Dawson  remarks, 
of  "  the  first  music  of  living 
things  that  Geology  as  yet 
reveals  to  us." 

Amongst  the  Mollusca,  the  Devonian  rocks  have  yielded  a 
great  number  of  the  remains  of  Sea-mosses  (Polyzod).  Some 
of  these  belong  to  the  ancient  type  Ptilodictya,  which  seems  to 
disappear  here,  or  to  the  allied  Clathropora  (fig.  90),  with  its 
fenestrated  and  reticulated  fronds.  We  meet  also  with  the 
graceful  and  delicate  stems  of  Ceriopora  (fig.  91). 

The  majority  of  the  Devonian  Polyzoa  belong,  however,  to 
the  great  and  important  Palaeozoic  group  of  the  Lace-corals 
(Fenestella,  figs.  92  and  94,  Retepora,  fig.  93,  Poly  pom,  and 
their  allies).  In  all  these  forms  there  is  a  horny  skeleton,  of  a 


Fig.  89. — Win^  of   Platephemera  antlqna. 
Devonian,  America.     (After  Dawson.) 


146 


HISTORICAL    PALEONTOLOGY. 


fan-like   or  funnel-shaped   form,   which   grew  attached  by  its 
base  to  some  foreign  body.     The  frond  consists  of  slightly- 


a 


Fig.   90.  — Fragment   of    Clnthropora   interiexta,   of   the 
natura1  size  and  enlarged.    Devonian,  Canada.     (Original.) 


Fig.  91.  —  Fragment  of 
Ceriopora.  H amiltonensis,  of 
the  natural  size  and  enlarg- 
ed. Devonian,  Canada.  (Ori- 
ginal.) 


diverging  or  nearly  parallel  branches,  which  are  either  united 
by  delicate  cross-bars,  or  which  bend  alternately  from  side  to 
side,  and  become  directly  united  with  one  another  at  short 
intervals — in  either  case  giving  origin  to  numerous  oval  or 


L. 


F'g.  92. —  Fragment  of  Fenestella  magn:fica, 
of  the  natural  size  and  enlarged.  Devonian, 
Canada.  (Original.) 


Fig.  93. — Fragment  of  Retcpora 
Phillips!,  of  the  natural  size  and 
enlarged.  Devonian,  Canada.  (Ori- 
ginal.) 


Fig.  94. — Fragment  of  Fenestella 
cribr<"-a,  of  the  natural  size  and  enlarg- 
ed. Devonian,  Canada.  (Original.) 


oblong  perforations,  which  communicate  to  the  whole  plant- 
like  colony  a  characteristic  netted  and  lace-like  appearance. 
On  one  of  its  surfaces — sometimes  the  internal,  sometimes  the 
external— the  frond  carries  a  number  of  minute  chambers  or 


DEVONIAN   AND   OLD   RED    PERIOD.  147 

"cells,"  which  are  generally  borne  in  rows  on  the  branches, 
and  of  which  each  originally  contained  a  minute  animal. 

The  Brachiopods  still  continue  to  be  represented  in  great 
force  through  all  the  Devonian  deposits,  though  not  occurring 
in  the  true  Old  Red  Sandstone.  Besides  such  old  types  as 
Orthis,  Strophomena,  Lingula,  Athyris,  and  Rhynchonella,  we 
find  some  entirely  new  ones ;  whilst  various  types  which  only 
commenced  their  existence  in  the  Upper  Silurian,  now  under- 
go a  great  expansion  and  development.  This  last  is  especially 
the  case  with  the  two  families  of  the  Spiriferida  and  the  Pro- 
ductida.  The  Spirifers^  in  particular,  are  especially  character- 
istic of  the  Devonian,  both  in  the  Old  and  New  Worlds — some 
of  the  most  typical  forms,  such  as  Spirifera  mucronata  (fig.  96), 
having  the  shell  "  winged,"  or  with  the  lateral  angles  prolonged 


Fig-    95-  —  Spirifera 
scrclf>tilis.  Devonian,  C'a-  Fig.  gb.  —  Spir'fera  mucronata.     Devonian,  America, 

nada.     (Afler  Billings.)  (After  Killings.) 

to  such  an  extent  as  to  have  earned  for  them  the  popular  name 
of  "  fossil-butterflies."  The  closely-allied  Spirifera  disjuncta 
occurs  in  Britain,  France,  Spain,  Belgium,  Germany,  Russia, 
and  China.  The  family  of  the  Productida  commenced  to  exist 
in  the  Upper  Silurian,  in  the  genus  Chonetes ;  and  we  shall 
heieafter  find  it  culminating  in  the  Carboniferous  in  many 
forms  of  the  great  genus  Producta*  itself.  In  the  Devonian 
period,  there  is  an  intermediate  state  of  things,  the  genus 
Chonetes  being  continued  in  new  and  varied  types,  and  the 
Carboniferous  Products  being  represented  by  many  forms  of 
the  allied  group  Productella.  Amongst  other  well-known  De- 
vonian Brachiopods  may  be  mentioned  the  two  long-lived  and 
persistent  types  Atrypa  reticularis.  (fig.  97)  and  Strophomcna 
rhomboidalis  (fig.  98).  The  former  of  these  commences  in  the 
Upper  Silurian,  but  is  more  abundantly  developed  in  the  De- 
vonian, having  a  geographical  range  that  is  nothing  less  than 
world-wide;  whilst  the  latter  commences  in  the  Lower  Silurian, 

*  The  name  of  this  genus  is  often  written  Productns,  just  as  Spirifera 
is  often  given  in  the  masculine  gender  as  Spirifer  (the  name  originally  given 
to  it).  The  masculine  termination  to  these  names  is,  however,  grammati- 
cally incorrect,  as  the  feminine  noun  cochlea  (shell)  is  in  these  cases  under- 
stood. 


148 


HISTORICAL   PALEONTOLOGY. 


and,  with  an  almost  equally  cosmopolitan  range,  survives  into 
the  Carboniferous  period. 


Fig.  97. — Atrypa  reticularis.     Upper  Silurian  and  Devonian  of  Europe 
and  America.     (After  Billings.) 

The  Bivalves  (Lamellibranchiata)  of  the  Devonian  call  for 
no  special  comment,  the  genera  Pterinea  and  Megalodon  being, 


Fig.  98. — Strophomena  rhomboidalis.     Lower  Silurian,  Upper  Silurian,  and 
Devonian  of  Europe  and  America. 

perhaps,  the  most  noticeable.  The  Univalves  (Gasteropods}, 
also,  need  not  be  discussed  in  detail,  though  many  interesting 
forms  of  this  group  are  known.  The  type  most  abundantly 
represented,  especially  \\\  America,  is  Platyceras  (fig.  99), 

comprising  thin,  wide  - 
mouthed  shells,  probably 
most  nearly  allied  to  the 
existing  "Bonnet-limpets," 
and  sometimes  attaining 
very  considerable  dimen- 
sions. We  may  also  note 
the  continuance  of  the 
genus  Euomphalus,  with 

Fig.   99.— Different   views  of  Platyceras  du-       its     discoidal     Spiral     shell. 
mosum,  of  the  natural  size.     Devonian,  Canada.         .  •,  rr  ,         ,     j 

(Original.)  Amongst    the   Heteropods, 

the  survival  of  Bellerophon 

is  to  be  recorded  ;  and  in  the  "  Winged-snails,"  or  Pteropods,  we 
find  new  forms  of  the  old  genera  Teutaculites  and  Conularia 


DEVONIAN   AND    OLD    RED    PERIOD. 


149 


(fig.  100).     The  latter,  with  its  fragile,  conical,  and  often  beauti- 
fully ornamented  shell,  is  especially  noticeable. 

The  remains  of  Cephalopoda  are  far  from  uncommon  in  the 
Devonian  deposits,  all  the  known  forms 
being  still  Tetrabranchiate.  Besides  the 
ancient  types  Orthoceras  and  Cyrtoceras, 
we  have  now  a  predominance  of  the 
spirally-coiled  chambered  shells  of  Goni- 
atites  and  Clymenia.  In  the  former  of 
these  the  shell  is  shaped  like  that  of  the 
Nautilus ;  but  the  partitions  between  the 
chambers  ("septa")  are  more  or  less 
lobed,  folded,  or  angulated,  and  the 
"  siphuncle"  runs  along  the  back  or  con- 
vex side  of  the  shell — these  being  char- 
acters which  approximate  Goniatites  to 
tiie  true  Ammonites  of  the  later  rocks. 
In  Clymenia,  on  the  other  hand,  whilst 
the  shell  (fig.  101)  is  coiled  into  a  flat 
spiral,  and  the  partitions  or  septa  are 
simple  or  only  slightly  lobed,  there  is  still 
this  difference,  as  compared  with  the  Nautilus,  that  the  tube  of 
the  siphuncle  is  placed  on  the  inner  or  concave  side  of  the 


Fig.  -Loo.—Conularia  or- 
nata,  of  the  natural  size. 
Devonian,  Europe. 


Fig.  101. — Clymenia  Sedgw!ckii.     Devonian,  Europe. 

shell.     The  species  of  Clymenia  are  exclusively  Devonian  in 


I5O  HISTORICAL   PAL/EONTOLOGY. 

their  range  ;  and  some  of  the  limestones  of  this  period  in 
Germany  are  so  richly  charged  with  fossils  of  this  genus  as  to 
have  received  the  name  of-"  Clymenien-kalk." 

The  sub-kingdom  of  the  Vertebrates  is  still  represented  by 
Fishes  only ;  but  these  are  so  abundant,  and  belong  to  such 
varied  types,  that  the  Devonian  period  has  been  appropriately 
called  the  "  Age  of  Fishes."  Amongst  the  existing  fishes  there 
are  three  great  groups  which  are  of  special  geological  import- 
ance, as  being  more  or  less  extensively  represented  in  past  time. 
These  groups  are  :  (i)  The  Bony  Fishes  (Teleostei],  comprising 
most  existing  fishes,  in  which  the  skeleton  is  more  or  less  com- 
pletely converted  into  bone ;  the  tail  is  symmetrically  lobed  or 
divided  into  equal  moieties ;  and  the  scales  are  usually  thin, 
horny,  flexible  plates,  which  overlap  one  another  to  a  greater 
or  less  extent.  (2)  The  Ganoid  Fishes  (Ganoidei),  comprising 
the  modern  Gar-pikes,  Sturgeons,  &c.,  in  which  the  skeleton 
usually  more  or  less  completely  retains  its  primitive  soft  and 
cartilaginous  condition  ;  the  tail  is  generally  markedly  unsym- 
metrical,  being  divided  into  two  unequal  lobes ;  and  the  scales 
(when  present)  have  the  form  of  plates  of  bone,  usually  cov- 
ered by  a  layer  of  shining  enamel.  These  scales  may  overlap  ; 
or  they  may  be  rhomboidal  plates,  placed  edge  to  edge  in 
oblique  rows  ;  or  they  have  the  form  of  large-sized  bony  plates, 
which  are  commonly  united  in  the  region  of  the  head  to  form 
a  regular  buckler.  (3)  The  Placoid  Fishes,  or  Elasmobranchii, 
comprising  the  Sharks,  Rays,  and  Chijncercz  of  the  present  day, 
in  which  the  skeleton  is  cartilaginous;  the  tail  is  unsymmetri- 
cally  lobed ;  and  the  scales  have  the  form  of  detached  bony 
plates  of  variable  size,  scattered  in  the  integument. 

It  is  to  the  two  last  of  these  groups  that  the  Devonian  fishes 
belong,  and  they  are  more  specially  referable  to  the  Ganoids. 
The  order  of  the  Ganoid  fishes  at  the  present  day  comprises 
but  some  seven  or  eight  genera,  the  species  of  which  princi- 
pally or  exclusively  inhabit  fresh  waters,  and  all  of  which  are 
confined  to  the  northern  hemisphere.  As  compared,  there- 
fore, with  the  Bony  fishes,  which  constitute  the  great  majority 
of  existing  forms,  the  Ganoids  form  but  an  extremely  small  and 
limited  group.  It  was  far  otherwise,  however,  in  Devonian 
times.  At  this  period,  the  bony  fishes  are  not  known  to  have 
come  into  existence  at  all,  and  the  Ganoids  held  almost  undis- 
puted possession  of  the  waters.  To  what  extent  the  Devonian 
Ganoids  were  confined  to  fresh  waters  remains  yet  to  be  proved  ; 
and  that  many  of  them  lived  in  the  sea  is  certain.  It  was 
formerly  supposed  that  the  Old  Red  Sandstone  of  Scotland 
and  Ireland,  with  its  abundant  fish-remains,  might  perhaps  be 
a  fresh-water  deposit,  since  the  habitat  of  its  fishes  is  uncer- 


DEVONIAN   AND   OLD   RED    PERIOD.  151 

tain,  and  it  contains  no  indubitable  marine  fossils.  It  has 
been  now  shown,  however,  that  the  marine  Devonian  strata  of 
Devonshire  and  the  continent  of  Europe  contain  some  of  the 
most  characteristic  of  the  Old  Red  Sandstone  fishes  of  Scot- 
land ;  whilst  the  undoubted  marine  deposit  of  the  Corniferous 
limestone  of  North  America  contains  numerous  shark-like  and 
Ganoid  fishes,  including  such  a  characteristic  Old  Red  genus 
as  Coccosteus.  There  can  be  little  doubt,  therefore,  but  that  the 
majority  of  the  Devonian  fishes  were  truly  marine  in  their  habits, 
though  it  is  probable  that  many  of  them  lived  in  shallow  water, 
in  the  immediate  neighbourhood  of  the  shore,  or  in  estuaries. 
The  Devonian  Ganoids  belong  to  a  number  of  groups  \  and 


Fig.  102. — Fishes  of  the  Devonian  rocks  of  America,  a.  Diagram  of  the  jaws  and  teeth 
of  Dinickthys  Hertzeri,  viewed  from  the  front,  and  greatly  reduced  ;  b,  Diagram  of  the 
skull  of  Macropetalichthys  Srtllivanti,  reduced  in  size  ;  c,  A  portion  of  the  enamelled  sur- 
face of  the  skull  of  the  same,  magnified  ;  d,  One  of  the  scales  of  Onychodus  sigmoides,  of 
the  iSatural  size  ;  e,  One  of  the  front  teeth  of  the  lower  jaw  of  the  same,  of  the  natural  size  \f, 
Fin-spine  of  Mach&racanthus  major,  a  shark-like  fish,  reduced  in  size.  (After  Newberry.) 

it  is  only  possible  to  notice  a  few  of -the  most  important  forms 
here.       The  modern  group  of  the  Sturgeons  is  represented, 


152  HISTORICAL   PALAEONTOLOGY. 

more  or  less  remotely,  by  a  few  Devonian  fishes — such  as  As- 
terosteus  ;  and  the  great  Macropetalichthys  of  the  Corniferous 
limestone  of  North  America  is  believed  by  Newberry  to  belong 
to  this  group,  In  this  fish  (fig.  102,  b)  the  skull  was  of  large 
size,  its  outer  surface  being  covered  with  a  tuberculated  en- 
amel ;  and,  as  in  the  existing  Sturgeons,  the  mouth  seems  to 
have  been  wholly  destitute  of  teeth.  Somewhat  allied,  also,  to 
the  Sturgeons,  is  a  singular  group  of  armoured  fishes,  which  is 
highly  characteristic  of  the  Devonian  of  Britain  and  Europe, 
and  less  so  of  that  of  America.  In  these  curious  forms  the 
head  and  front  extremity  of  the  body  were  protected  by  a 
buckler  composed  of  large  enamelled  plates,  more  or  less 
firmly  united  to  one  another  [whilst  the  hinder  end  of  the  body 
was  naked,  or  was  protected  with  small  scales.  Some  forms  of 
this  group — such  as  Fteraspis  and  Coccosteus — date  from  the 
Upper  Silurian ;  but  they  attain  their  maximum  in  the  Devo- 
nian, and  none  of  them  are  known  to  pass  upwards  into  the 
overlying  Carboniferous  rocks.  Amongst  the  most  character- 
istic forms  of  this  group  may  be  mentioned  Cephalaspis  (fig. 
103)  and  Ptcrichthys  (fig.  104).  In  the  former  of  these  the 


Fig.  103.— Cephalaspis  Lyellii.     Old  Red  Sandstone,  Scotland.     (After  Page.) 

head-shield  is  of  a  crescentic  shape,  having  its  hinder  angles 
produced  backwards  into  long  "  horns,"  giving  it  the  shape  of 
a  "saddler's  knife."  No  teeth  have  been  discovered;  but  the 
body  was  covered  with  small  ganoid  scales,  and  there  was  an 
unsymmetrical  tail-fin.  In  Ptcrichthys — which,  like  the  preced- 
ing, was  first  brought  to  light  by  the  labours  of  Hugh  Miller — 
the  whole  of  the  head  and  the  front  part  of  the  body  were  de- 
fended by  a  buckler  of  firmly-united  enamelled  plates,  whilst 
the  rest  of  the  body  was  covered  with  small  scales.  The  form 
of  the  "  pectoral  fins  "  was  quite  unique  —  these  having  the 
shape  of  two  long,  curved  spines,  somewhat  like  wings,  covered 
by  finely-tuberculated  ganoid  plates.  All  the  preceding  forms 


DEVONIAN  AND  OLD  RED  PERIOD.  153 

of  this  group  are  of  small  size  ;  but  few  fishes,  living  or  extinct, 
could  rival  the  proportions  of  the  great  Dinichthys,  referred  to 


Fig.  104. — Pterickthys  cornutus.     Old  Red  Sandstone,  Scotland.     (After  Agassiz.) 

this  family  by  Newberry.  In  this  huge  fish  (fig.  102,  a)  the 
head  alone  is  over  three  feet  in  length,  and  the  body  is  sup- 
posed to  have  been  twenty-five  or  thirty  feet  long.  The  head 
was  protected  by  a  massive  cuirass  of  bony  plates  firmly  articu- 
lated together,  but  the  hinder  end  of  the  body  seems  to  have 
been  simply  enveloped  in  a  leathery  skin.  The  teeth  are  of 
the  most  formidable  description,  consisting  in  both  jaws  of 
serrated  dental  plates  behind,  and  in  front  of  enormous  coni- 
cal tusks  (fig.  102,  a).  Though  immensely  larger,  the  teeth  of 
Dinichthys  present  a  curious  resemblance  to  those  of  the  exist- 
ing Mud-fishes  (Lepido siren). 

In  another  great  group  of  Devonian  Ganoids,  we  meet  with 
fishes  more  or  less  closely  allied  to  the  living  Polypteri  (fig. 
105)  of  the  Nile  and  Senegal.  In  this  group  (fig.  106)  the 
pectoral  fins  consist  of  a  central  scaly  lobe  carrying  the  fin- 
rays  on  both  sides,  the  scales  being  sometimes  rounded  and 
overlapping  (fig.  106),  or  more  commonly  rhomboidal  and 
placed  edge  to  edge  (fig.  105,  A).  Numerous  forms  of  these 
"  Fringe-finned  "  Ganoids  occur  in  the  Devonian  strata,  such 
as  Holoptychius,  Glyptolcenms,  Osteolepis,  Phanerophuron,  &c. 
To  this  group  is  also  to  be  ascribed  the  huge  Onychodus  (fig. 
102,  //and  e),  with  its  large,  rounded,  overlapping  scales,  an 
inch  in  diameter,  and  its  powerful  pointed  teeth.  It  is  to  be 
remembered,  however,  that  some  of  these  "  Fringe  -finned" 
Ganoids  are  probably  referable  to  the  small  but  singular  group 
of  the  "  Mud-fishes  "  (Dipnoi),  represented  at  the  present  day 
by  the  singular  Lepidosiren  of  South  America  and  Africa,  and 
the^Ceratadus  of  the  rivers  of  Queensland. 

Leaving  the  Ganoid  fishes,  it  still  remains  to  be  noticed  that 
the  Devonian  deposits  have  yielded  the  remains  of  a  number 
of  fishes  more  or  less  closely  allied  to  the  existing  Sharks, 


154 


HISTORICAL   PAL/EONTOLOGV. 


Rays,  and   Chimcerce  (the  Elasmobranchii).      The  majority  of 
the  forms  here  alluded  to  are  allied  not  to  the  true  Sharks  and 


Fig.  105. — A,  Polypterns,  a  recent  Ganoid  fish  ;  B,  Osteolefis,  a  Devonian  Ganoid ; 
a  a,  Pectoral  fins,  showing  the  fin-rays  arranged  round  a  central  lobs. 

Dog-fishes,  but  to  the  more  peaceable  "  Port  Jackson  Sharks," 
with  their  blunt  teeth,  adapted  for  crushing  the  shells  of  Mol- 
luscs. The  collective  name  of  "  Cestracionts  "  is  applied  to 
these ;  and  we  have  evidence  of  their  past  existence  in  the 


Fig.  106. — H oloptychiits  nobilissimus,  restored.     Old  Red  Sandstone,  Scotland. 
A,  Scale  of  the  same. 

Devonian  seas  both  by  their  teeth,  and  by  the  defensive  spines 
which  were  implanted  in  front  of  a  greater  or  less  number  of 
the  fins.  These  are  bony  spines,  often  variously  grooved, 
serrated,  or  ornamented,  with  hollow  bases,  implanted  in  the 
integument,  and  capable  of  being  erected  or  depressed  at  will. 


DEVONIAN    AND   OLD   RED    PERIOD.  155 

Many  of  these  "  fin-spines  "  have  been  preserved  to  us  in  the 
fossil  condition,  and  the  Devonian  rocks  have  yielded  examples 
belonging  to  many  genera.  As  some  of  the  true  Sharks  and 
Dog-fishes,  some  of  the  Ganoids,  and  even  some  Bony  Fishes, 
possess  similar  defences,  it  is  often  a  matter  of  some  uncer- 
tainty to  what  group  a  given  spine  is  to  be  referred.  One  of 
these  spines,  belonging  to  the  genus  Machar acanthus,  from  the 
Devonian  rocks  of  America,  has  been  figured  in  a  previous 
illustration  (fig.  io2,/). 

In  conclusion,  a  very  few  words  may  be  said  as  to  the 
validity  of  the  Devonian  series  as  an  independent  system  of 
rocks,  preserving  in  its  successive  strata  the  record  of  an 
independent  system  of  life.  Some  high  authorities  have  been 
inclined  to  the  view  that  the  Devonian  formation  has  in  nature 
no  actual  existence,  but  that  it  is  made  up  partly  of  beds 
which  should  be  referred  to  the  summit  of  the  Upper  Silurian, 
and  partly  of  beds  which  properly  belong  to  the  base  of  the 
Carboniferous.  This  view  seems  to  have  been  arrived  at  in 
consequence  of  a  too  exclusive  study  of  the  Devonian  series 
of  the  British  Isles,  where  the  physical  succession  is  not  wholly 
clear,  and  where  there  is  a  striking  discrepancy  between  the 
organic  remains  of  those  two  members  of  the  series  which  are 
known  as  the  "Old  Red 'Sandstone"  and  the  "Devonian'"' 
rocks  proper.  This  discrepancy,  however,  is  not  complete ; 
and,  as  we  have  seen,  can  be  readily  explained  on  the  sup- 
position that  the  one  group  of  rocks  presents  us  with  the 
shallow  water  and  littoral  deposits  of  the  period,  while  in  the 
other  we  are  introduced  to  the  deep-sea  accumulations  of  the 
same  period.  Nor  can  the  problem  at  issue  be  solved  by  an 
appeal  to  the  phenomena  of  the  British  area  alone,  be  the 
testimony  of  these  what  it  may.  As  a  matter  of  fact,  there  is 
at  present  no  sufficient  ground  for  believing  that  there  is  any 
irreconcilable  discordance  between  the  succession  of  rocks 
and  of  life  in  Britain  during  the  period  which  elapsed  between 
the  deposition  of  the  Upper  Ludlow  and  the  formation  of  the 
Carboniferous  Limestone,  and  the  order  of  the  same  phe- 
nomena during  the  same  period  in  other  regions.  Some  of 
the  Devonian  types  of  life,  as  is  the  case  with  all  great  forma- 
tions, have  descended  unchanged  from  older  types ;  others 
pass  upwards  unchanged  to  the  succeeding  period :  but  the 
fauna  and  flora  of  the  Devonian  period  are,  as  a  whole,  quite 
distinct  from  those  of  the  preceding  Silurian  or  the  succeeding 
Carboniferous ;  and  they  correspond  to  an  equally  distinct 
rock-system,  which  in  point  of  time  holds  an  intermediate 
position  between  the  two  great  groups  just  mentioned.  As 


HISTORICAL   PAL/EONTOLOGY. 

before  remarked,  this  conclusion  may  be  regarded  as  suffi- 
ciently proved  even  by  the  phenomena  of  the  British  area ; 
but  it  may  be  said  to  be  rendered  a  certainty  by  the  study  of 
the  Devonian  deposits  of  the  continent  of  Europe — or,  still 
more,  by  the  investigation  of  the  vast,  for  the  most  part  un- 
interrupted and  continuous  series  of  sediments  which  com- 
menced to  be  laid  down  in  North  America  at  the  beginning  of 
the  Upper  Silurian,  and  did  not  cease  till,  at  any  rate,  the  close 
of  the  Carboniferous. 


LITERATURE. 

The  following  list  comprises  the  more  important  works  and  memoirs  to 
which  the  student  of  Devonian  rocks  and  fossils  may  refer  :  — 

(1)  '  Siluria.'     Sir  Roderick  Murchison. 

(2)  'Geology   of  Russia  in   Europe.'     Murchison    (together   with    De 

Verneuil  and  Count  von  Keyserling). 

(3)  "  Classification  of  the  Older  Rocks  of  Devon  and  Cornwall " — '  Proc. 

Geol.  Soc.,'  vol.  iii.,  1839.     Sedgwick  and  Murchison. 

(4)  "  On  the  Physical  Structure  of  Devonshire  ;"  and  on  the  "  Classifi- 

cation of  the  Older  Stratified  Rocks  of  Devonshire  and  Cornwall  " 
—  'Trans.  Geol.  Soc.,'  vol.  v.,  1840.     Sedgwick  and  Murchison. 

(5)  "  On  the  Distribution  and  Classification  of  the  Older  or  Palaeozoic 

Rocks  of  North  Germany  and  Belgium" — '  Geol.  Trans.,'  2d  ser., 
vol.  vi.,  1842.     Sedgwick  and  Murchison. 

(6)  '  Report  on  the  Geology  of  Cornwall,  Devon,  and  West  Somerset.' 

De  la  Beche. 

(7)  'Memoirs   of  the   Geological    Survey   of    Ireland   and   Scotland.' 

Jukes  and  Geikie. 

(8)  "On  the  Carboniferous  Slate  (or  Devonian  Rocks)  and  the  Old 

Red  Sandstone  of  South  Ireland  and  North  Devon" — 'Quart. 
Journ.  Geol.  Soc.,'  vol.  xxii.     Jukes. 

(9)  "  On  the  Physical  Structure  of  West  Somerset  and  North  Devon  ;  " 

and  on  the  "  Pal?eontological  Value  of  Devonian  Fossils" — 'Quart. 
Journ.  Geol.  Soc.,'  vol.  iii.     Etheridge. 

(10)  "  On  the  Connection  of  the  Lower,  Middle,  and  Upper  Old  Red 

Sandstone  of  Scotland" — 'Trans.  Edin.  Geol.  Soc.,'  vol.  i.  part  ii. 
Powrie. 

(11)  'The  Old  Red  Sandstone,'  'The  Testimony  of  the  Rocks,'  and 

'  Footprints  of  the  Creator.'     Hugh  Miller. 

(12)  "  Report  on  the  4th  Geological  District" — '  Geology  of  New  York,' 

vol.  iv.     James  Hall. 

(13)  'Geology  of  Canada,'  1863.     Sir  W.  E.  Logan. 

(14)  '  Acadian  Geology. '     Dawson. 

(15)  '  Manual  of  Geology.'     Dana. 

(16)  '  Geological  Survey  of  Ohio,'  vol.  i. 

(17)  'Geological  Survey  of  Illinois,'  vol.  i. 

(18)  'Palaeozoic   Fossils    of    Cornwall,    Devon,    and   West   Somerset.' 

Phillips. 

(19)  '  Recherches  sur  les  Poissons  Fossiles.'     Agassiz. 

(20)  '  Poissons  de  1'Old  Red.'     Agassiz. 

(21)  "On  the  Classification  of  Devonian  Fishes" — 'Mem.  Geol.  Survey 

of  Great  Britain,'  Decac  e  X.     Huxley. 


THE   CARBONIFEROUS    PERIOD.  157 

(22)  '  Monograph  of  the   Fishes  of  the  Old  Red  Sandstone  of  Britain.' 

(Palaeontographical  Society).     Powrie  and  Lankester. 

(23)  '  Fishes  of  the  Devonian  System,   Palaeontology  of  Ohio.'     New- 

berry. 

(24)  '  Monograph    of  British   Trilobites '    (Palaeontographical    Society). 

Salter. 

(25)  '  Monograph  of  British  Merostomata '  (Palgeontographical  Society). 

Henry  Woodward. 

(26)  '  Monograph  of  British  Brachiopoda  '  (Palaeontographical  Society). 

Davidson. 

(27)  '  Monograph  of  British  Fossil  Corals'  (Palseontographical  Society). 

Milne-Edwards  and  Haime. 

(28)  '  Polypiers    Foss.    des    Terrains     Paleozoiques. '      Milne-Edwards 

and  Jules  Haime. 

(29)  "  Devonian  Fossils  of  Canada  West " — '  Canadian  Journal,'  new  ser., 

vols.  iv.-vi.      Billings. 

(30)  'Palaeontology  of  New  York,' vol.  iv.     James  Hall. 

(31)  'Thirteenth,  Fifteenth,  and  Twenty-third  Annual  Reports  on  the 

State  Cabinet.'    James  Hall. 

(32)  '  Palaeozoic  Fossils  of  Canada,'  vol.  ii.     Billings. 

(33)  '  Reports  on  the  Palaeontology  of  the  Province  of  Ontario  for  1874 

and  1875.'     Nicholson. 

(34)  "  The  Fossil  Plants  of  the  Devonian  and  Upper  Silurian  Formations 

of  Canada" — '  Geol.  Survey  of  Canada. '     Dawson. 

(35)  '  Petrefacta  Germaniae.'     Gold  fuss. 

(36)  '  Versteinerungen  der  Grauwacken -formation.'  &c.     Geinitz. 

(37)  '  Beitrag  zur  Palaeontologie  des  Thiiringer-Waldes.'     Richter  and 

Unger. 

(38)  '  Ueber  die  Placodermen  der  Devonischen  System.'     Pander. 

(39)  '  Die  Gattungen  der  Fossilen  Pflanzen.'     Gceppert. 

(40)  '  Genera  et  Species  Plantarum  Fossilium.'     Unger. 


CHAPTER    XII. 
THE    CARBONIFEROUS  PERIOD. 

Overlying  the  Devonian  formation  is  the  great  and  import- 
ant series  of  the  Carboniferous  Rocks,  so  called  because  workable 
beds  of  coal  are  more  commonly  and  more  largely  developed 
in  this  formation  than  in  any  other.  Workable  coal-seams, 
however,  occur  in  various  other  formations  (Jurassic,  Cretace- 
ous, Tertiary),  so  that  coal  is  not  an  exclusively  Carboniferous 
product ;  whilst  even  in  the  Coal-measures  themselves  the  coal 
bears  but  a  very  small  proportion  to  the  total  thickness  of 
strata,  occurring  only  in  comparatively  thin  beds  intercalated 
in  a  great  series  of  sandstones,  shales,  and  other  genuine 
aqueous  sediments. 
12 


158  HISTORICAL   PALAEONTOLOGY. 

Stratigraphically,  the  Carboniferous  rocks  usually  repose 
conformably  upon  the  highest  Devonian  beds,  so  that  the  line 
of  demarcation  between  the  Carboniferous  and  Devonian  for- 
mations is  principally  a  palaeontological  one,  founded  on  the 
observed  differences  in  the  fossils  of  the  two  groups.  On  the 
other  hand,  the  close  of  the  Carboniferous  period  seems  to 
have  been  generally,  though  not  universally,  signalised  by 
movements  of  the  crust  of  the  earth,  so  that  the  succeeding 
Permian  beds  often  lie  unconformably  upon  the  Carboniferous 
sediments. 

Strata  of  Carboniferous  age  have  been  discovered  in  almost 
every  large  land-area  which  has  been  sufficiently  investigated ; 
but  they  are  especially  largely  developed  in  Britain,  in  various 
parts  of  the  continent  of  Europe,  and  in  North  America. 
Their  general  composition,  however,  is,  comparatively  speak- 
ing, so  uniform,  that  it  will  suffice  to  take  a  comprehensive 
view  of  the  formation  without  considering  any  one  area  in 
detail,  though  in  each  region  the  subdivisions  of  the  formation 
are  known  by  distinctive  local  names.  Taking  such  a  com- 
prehensive view,  it  is  found  that  the  Carboniferous  series  is 
generally  divisible  into  a  Lower  and  essentially  calcareous 
group  (the  "Sub-Carboniferous"  or  "Carboniferous  Lime- 
stone ") ;  a  Middle  and  principally  arenaceous  group  (the 
"  Millstone  Grit");  and  an  Upper  group,  of  alternating  shales 
and  sandstones,  with  workable  seams  of  coal  (the  "  Coal- 
measures  "). 

I.  The  Carboniferous,  Sub- Carboniferous,  or  Mountain  Lime- 
stone Series  constitutes  the  general  base  of  the  Carboniferous 
system.  As  typically  developed  in  Britain,  the  Carboniferous 
Limestone  is  essentially  a  calcareous  formation,  sometimes 
consisting  of  a  mass  of  nearly  pure  limestone  from  1000  to 
2000  feet  in  thickness,  or  at  other  times  of  successive  great 
beds  of  limestone  with  subordinate  sandstones  and  shales. 
In  the  north  of  England  the  base  of  the  series  consists  of 
pebbly  conglomerates  and  coarse  sandstones;  and  in  Scot- 
land generally,  the  group  is  composed  of  massive  sandstones 
with  a  comparatively  feeble  development  of  the  calcareous 
element.  In  Ireland,  again,  the  base  of  the  Carboniferous 
Limestone  is  usually  considered  to  be  formed  by  a  locally- 
developed  group  of  grits  and  shales  (the  "  Coomhola  Grits  " 
and  "Carboniferous  Slate"),  which  attain  the  thickness  of 
about  5000  feet,  and  contain  an  intermixture  of  Devonian 
with  Carboniferous  types  of  fossils.  Seeing  that  the  Devonian 
formation  is  generally  conformable  to  the  Carboniferous,  we 
need  feel  no  surprise  at  this  intermixture  of  forms  ;  nor  does  it 


THE   CARBONIFEROUS   PERIOD.  159 

appear  to  be  of  great  moment  whether  these  strata  be  referred 
to  the  former  or  to  the  latter  series.  Perhaps  the  most  satis- 
factory course  is  to  regard  the  Coomhola  Grits  and  Carbon- 
iferous Slates  as  "  passage-beds  "  between  the  Devonian  and 
Carboniferous ;  but  any  view  that  may  be  taken  as  to  the 
position  of  these  beds,  really  leaves  unaffected  the  integrity 
of  the  Devonian  series  as  a  distinct  life-system,  which,  on  the 
whole,  is  more  closely  allied  to  the  Silurian  than  to  the  Car- 
boniferous. In  North  America,  lastly,  the  Sub-Carboniferous 
series  is  never  purely  calcareous,  though  in  the  interior  of  the 
continent  it  becomes  mainly  so.  In  other  regions,  however, 
it  consists  principally  of  shales  and  sandstones,  with  subor- 
dinate beds  of  limestone,  and  sometimes  with  thin  beds  of 
coal  or  deposits  of  clay-ironstone. 

II.  The  Millstone  Grit,— The  highest  beds  of  the  Carbon- 
iferous Limestone  series  are  succeeded,  generally  with  perfect 
conformity,  by  a  series  of  arenaceous  beds,  usually  known  as 
the  Millstone  Grit.     As  typically  developed  in  Britain,  this 
group  consists  of  hard  quartzose  sandstones,  often  so  large- 
grained  and  coarse  in  texture  as  to  properly  constitute  fine 
conglomerates.     In  other  cases  there  are  regular  conglomer- 
ates, sometimes  with  shales,  limestones,  and  thin  beds  of  coal — 
the  thickness  of  the  whole  series,  when  well  developed,  varying 
from  1000  to  5000  feet.     In  North  America,  the  Millstone 
Grit  rarely  reaches  1000  feet  in  thickness ;  and,  like  its  Brit- 
ish equivalent,  consists  of  coars.e  sandstones  and  grits,  some- 
times with  regular  conglomerates.     Whilst  the  Carboniferous 
Limestone   was   undoubtedly  deposited  in  a  tranquil  ocean 

.of  considerable  depth,  the  coarse  mechanical  sediments  of 
the  Millstone  Grit  indicate  the  progressive  shallowing  of 
the  Carboniferous  seas,  and  the  consequent  supervention 
of  shore-conditions. 

III.  The   Coal-measures. — The    Coal-measures    properly  so 
called  rest  conformably  upon  the  Millstone  Grit,  and  usually 
consist  of  a  vast  series  of  sandstones,  shales,  grits,  and  coals, 
sometimes  with  beds  of  limestone,  attaining  in  some  regions  a 
total  thickness  of  from  7000  to  nearly  14,000  feet.     Beds  of 
workable  coal  are  by  no  means  unknown  in  some  areas  in  the 
inferior  group  of  the  Sub-Carboniferous;  but  the  general  state- 
ment is  true,  that  coal  is  mostly  obtained  from  the  true  Coal- 
measures — the  largest  known,  and  at  present   most   produc- 
tive  coal-fields  of  the  world  being  in  Great   Britain,  North 
America,    and    Belgium.      Wherever    they    are    found,    with 
limited   exceptions,    the    Coal  -  measures    present   a    singular 
general  uniformity   of    mineral    composition.     They    consist, 


1 00  HISTORICAL   PALAEONTOLOGY. 

namely,  of  an  indefinite  alternation  of  beds  of  sandstone, 
shale,  and  coal,  sometimes  with  bands  of  clay-ironstone  or  beds 
of  limestone,  repeated  in  no  constant  order,  but  sometimes 
attaining  the  enormous  aggregate  thickness  of  14,000  feet,  or 
little  short  of  3  miles.  The  beds  of  coal  differ  in  number  and 
thickness  in  different  areas,  but  they  seldom  or  never  exceed 
one-fiftieth  part  of  the  total  bulk  of  the  formation  in  thickness. 
The  characters  of  the  coal  itself,  and  the  way  in  which  the 
coal-beds  were  deposited,  will  be  briefly  alluded  to  in  speaking 
of  the  vegetable  life  of  the  period.  In  Britain,  and  in  the  Old 
World  generally,  the  Coal-measures  are  composed  partly'  of 
genuine  terrestrial  deposits — such  as  the  coal — and  partly  of 
sediments  accumulated  in  the  fresh  or  brackish  waters  of  vast 
lagoons,"  estuaries,  and  marshes.  The  fossils  of  the  Coal- 
measures  in  these  regions  are  therefore  necessarily  the  remains 
either  of  terrestrial  plants  and  animals,  or  of  such  forms  of 
life  as  inhabit  fresh  or  brackish  waters,  the  occurrence  of  strata 
with  marine  fossils  being  quite  a  local  and  occasional  phe- 
nomenon. In  various  parts  of  North  America,  on  the  other 
hand,  the  Coal-measures,  in  addition  to  sandstones,  shales, 
coal-seams,  and  bands  of  clay-ironstone,  commonly  include 
beds  of  limestone,  charged  with  marine  remains,  and  indicating 
marine  conditions.  The  subjoined  section  (fig.  107)  gives,  in 
a  generalised  form,  the  succession  of  the  Carboniferous  strata 
in  such  a  British  area  as  the  north  of  England,  where  the  series 
is  developed  in  a  typical  form. 

As  regards  the  life  of  the  Carboniferous  period,  we  naturally 
find,  as  has  been  previously  noticed,  great  differences  in  dif- 
ferent parts  of  the  entire  series,  corresponding  to  the  different 
mode  of  origin  of  the  beds.  Speaking  generally,  the  Lower 
Carboniferous  (or  the  Sub-Carboniferous)  is  characterised  by 
the  remains  of  marine  animals  ;  whilst  the  Upper  Carbon- 
iferous (or  Coal-measures)  is  characterised  by  the  remains 
of  plants  and  terrestrial  animals.  In  all  those  cases,  how- 
ever, in  which  marine  beds  are  found  in  the  series  of  the 
Coal-measures,  as  is  common  in  America,  then  we  find  that  the 
fossils  agree  in  their  general  characters  with  those  of  the  older 
marine  deposits  of  the  period. 

Owing  to  the  fact  that  coal  is  simply  compressed  and  other- 
wise altered  vegetable  matter,  and  that  it  is  of  the  highest 
economic  value  to  man,  the  Coal-measures  have  been  more 
thoroughly  explored  than  any  other  group  of  strata  of  equiva- 
lent thickness  in  the  entire  geological  series.  Hence  we  have 
already  a  very  extensive  acquaintance  with  the  plants  of  the 
Carboniferous  period  ;  and  our  knowledge  on  this  subject  is 


THE  CARBONIFEROUS   PERIOD.  l6l 

daily  undergoing  increase.     It  is  not  to  be  supposed,  however, 
that   the   remains   of  plants   are   found   solely  in  the  Coal> 

GENERALISED  SECTION  OF  THE  CARBONIFEROUS  STRATA 
OF  THE  NORTH  OF  ENGLAND. 


Fig.  107. 


13 


8-* 


•<  o 
u 


£::* : W  \">  I*  :•::••-. ?».#....••• 

"%  "  ii  '"  .v  fli  "u"  »".."\.3S; 

I.  "  I,  »     "     ti  „ '» 


,.«  ,,»  u  »  i.  » 


_1J — U — u     ii      h    ii    ii   n    n    ir 


II    II 


Permian  (New  Red  Sand- 
stone). 


—  Coal-measures. 


-  Millstone  Grit. 


Yoredale  Series. 


—  Scar-Limestone  Series. 


Basement  r>eds  (Conglom- 
erates and  Sandstones). 


measures  ;  for  though  most  abundant  towards  the  summit, 
they  are  found  in  less  numbers  in  all  parts  of  the  series. 
Wherever  found,  they  belong  to  the  same  great  types  of  vege- 


1 62  HISTORICAL  PALEONTOLOGY. 

tation  ;  but,  before  reviewing  these,  a  few  words  must  be  said 
as  to  the  origin  and  mode  of  formation  of  coal. 

The  coal-beds,  as  before  mentioned,  occur  interstratified 
with  shales,  sandstones,  and  sometimes  limestones  ;  and  there 
may,  within  the  limits  of  a  single  coal-field,  be  as  many  as  80 
or  100  of  such  beds,  placed  one  above  the  other  at  different 
levels,  and  varying  in  thickness  from  a  few  inches  up  to  20  or 
30  feet.  As  a  general  rule,  each  bed  of  coal  rests  upon  a  bed 
of  shale  or  clay,  which  is  termed  the  "under-day,"  and  in 
which  are  found  numerous  roots  of  plants ;  whilst  the  strata 
immediately  on  the  top  of  the  coal  may  be  shaly  or  sandy, 
but  in  either  case  are  generally  charged  with  the  leaves  and 
stems  of  plants,  and  often  have  upright  trunks  passing  vertically 
through  them.  When  we  add  to  this  that  the  coal  itself  is, 
chemically,  nearly  wholly  composed  of  carbon,  and  that  its 
microscopic  structure  shows  it  to  be  composed  almost  entirely 
of  fragments  of  stems,  leaves,  bark,  seeds,  and  vegetable  debris 
derived  from  land-plants,  we  are  readily  enabled  to  understand 
how  the  coal  was  formed.  The  "under -day"  immediately 
beneath  the  coal-bed  represents  an  old  land-surface — some- 
times, perhaps,  the  bottom  of  a  swamp  or  marsh,  covered 
with  a  luxuriant  vegetation  ;  the  coal  bed  itself  represents  the 
slow  accumulation,  through  long  periods,  of  the  leaves,  seeds, 
fruits,  stems,  and  fallen  trunks  of  this  vegetation,  now  hardened 
and  compressed  into  a  fraction  of  its  original  bulk  by  the  pres- 
sure of  the  superincumbent  rocks ;  and  the  strata  of  sand  or 
shale  above  the  coal-bed — the  so-called  "roof"  of  the  coal- 
represent  sediments  quietly  deposited  as  the  land,  after  a  long 
period  of  repose,  commenced  to  sink  beneath  the  sea.  On 
this  view,  the  rank  and  long-continued  vegetation  which  gave 
rise  to  each  coal-bed  was  ultimately  terminated  by  a  slow 
depression  of  the  surface  on  which  the  plants  grew.  The 
land-surface  then  became  covered  by  the  water,  and  aqueous 
sediments  were  accumulated  to  a  greater  or  less  thickness  upon 
the  dense  mass  of  decaying  vegetation  below,  enveloping  any 
trunks  of  trees  which  might  still  be  in  an  erect  position,  and 
preserving  between  their  layers  the  leaves  and  branches  of 
plants  brought  down  from  the  neighbouring  land  by  streams, 
or  blown  into  the  water  by  the  wind.  Finally,  there  set  in  a 
slow  movement  of  elevation, — the  old  land  again  reappeared 
above  the  water ;  a  new  and  equally  luxuriant  vegetation 
flourished  upon  the  new  land-surface ;  and  another  coal-bed 
was  accumulated,  to  be  preserved  ultimately  in  a  similar 
fashion.  Some  few  beds  of  coal  may  have  been  formed  by 
drifted  vegetable  matter  brought  down  into  the  ocean  by  rivers, 


THE   CARBONIFEROUS   PERIOD.  163 

and  deposited  directly  on  the  bottom  of  the  sea ;  but  in  the 
majority  of  cases  the  coal  is  undeniably  the  result  of  the  slow 
growth  and  decay  of  plants  in  situ;  and  as  the  plants  of  the 
coal  are  not  marine  plants,  it  is  necessary  to  adopt  some  such 
theory  as  the  above  to  account  for  the  formation  of  coal- 
seams.  By  this  theory,  as  is  obvious,  we  are  compelled  to 
suppose  that  the  vast  alluvial  and  marshy  flats  upon  which  the 
coal-plants  grew  were  liable  to  constantly-recurring  oscillations 
of  level,  the  successive  land-surfaces  represented  by  the  suc- 
cessive coal-beds  of  any  coal-field  being  thus  successively 
buried  beneath  accumulations  of  mud  or  sand.  We  have  no 
need,  however,  to  suppose  that  these  oscillations  affected  large 
areas  at  the  same  time ;  and  geology  teaches  us  that  local 
elevations  and  depressions  of  the  land  have  been  matters  of 
constant  occurrence  throughout  the  whole  of  past  time. 

All  the  varieties  of  coal  (bituminous  coal,  anthracite,  cannel- 
coal,  &c.)  show  a  more  or  less  distinct  "lamination" — that  is 
to  say,  they  are  more  or  less  obviously  composed  of  successive 
thin  layers,  differing  slightly  in  colour  and  texture.  All  the 
varieties  of  coal,  clso,  consist  chemically  of  carbon,  with  vary- 
ing proportions  of  certain  gaseous  constituents  and  a  small 
amount  of  incombustible  mineral  or  "  ash."  By  cutting  thin 
and  transparent  slices  of  coal,  we  are  further  enabled,  by 
means  of  the  microscope,  to  ascertain  precisely  not  only  that 
the  carbon  of  the  coal  is  derived  from  vegetables,  but  also,  in 
many  cases,  what  kinds  of  plants,  and  what  parts  of  these,  enter 
into  the  formation  of  coal.  When  examined  in  this  way,  all 
coals  are  found  to  consist  more  or  less  entirely  of  vegetable 
matter;  but  there  is  considerable  difference  in  different  coals  as 
to  the  exact  nature  of  this.  By  Professor  Huxley  it  has  been 
shown  that  many  of  the  English  coals  consist  largely  of  ac- 
cumulations of  rounded  discoidal  sacs  or  bags,  which  are 
unquestionably  the  seed-vessels  or  "  spore-cases  "  of  certain  of 
the  commoner  coal-plants  (such  as  the  Lepidodend.ro] .  The 
best  bituminous  coals  seem  to  be  most  largely  composed  of 
these  spore-cases ;  whilst  inferior  kinds  possess  a  progressively 
increasing  amount  of  the  dull  carbonaceous  substance  which  is 
known  as  "mineral  charcoal,"  and  which  is  undoubtedly  com- 
posed of  "  the  stems  and  leaves  of  plants  reduced  to  little 
more  than  their  carbon, "  On  the  other  hand,  Principal  Daw- 
son  finds  that  the  American  coals  only  occasionally  exhibit 
spore-cases  to  any  extent,  but  consist  principally  of  the  cells, 
vessels,  and  fibres  of  the  bark,  integumentary  coverings,  and 
woody  portions  of  the  Carboniferous  plants. 

The  number  of  plants  already  known  to  have  existed  during 


1 64  HISTORICAL   PAL/EONTOLOGY. 

the  Carboniferous  period  is  so  great,  that  nothing  more  can  be 
done  here  than  to  notice  briefly  the  typical  and  characteristic 
groups  of  these — such  as  the  Ferns,  the  Catamites,  the  Lepido- 
dendroids,  the  Sigillarioids,  and  the  Conifers. 

In  accordance  with  M.  Brongniart's  generalisation,  that 
the  Palaeozoic  period  is,  botanically  speaking,  the  "Age  of 
Acrogens,"  we  find  the  Carboniferous  plants  to  be  still  mainly 
referable  to  the  Flowerless  or  "  Cryptogamous  "  division  of  the 
vegetable  kingdom.  The  flowering  or  "  Phanerogamous " 
plants,  which  form  the  bulk  of  our  existing  vegetation,  are  hardly 
known,  with  certainty,  to  have  existed  at  all  in  the  Carbon- 
iferous era,  except  as  represented  by  trees  related  to  the  existing 


Fig.  108. — Odontopteris  Schlotheimii.     Carboniferous,  Europe  and  North  America. 

Pines  and  Firs,  and  possibly  by  the  Cycads  or  "false  palms."* 
Amongst  the  "  Cryptogams,"  there  is  no  more  striking  or 
beautiful  group  of  Carboniferous  plants  than  the  Ferns.  .Re- 
mains of  these  are  found  all  through  the  Carboniferous,  but  in 
exceptional  numbers  in  the  Coal-measures,  and  include  both 
herbaceous  forms  like  the  majority  of  existing  species,  and 
arborescent  forms  resembling  the  living  Tree-ferns  of  New 
Zealand.  Amongst  the  latter,  together  with  some  new  types, 
are  examples  of  the  genera  Psaronius  and  Caulopteris,  both  of 

*  Whilst  the  vegetation  of  the  Coal-period  was  mainly  a  terrestrial  one, 
aquatic  plants  are  not  unknown.  Sea-weeds  (such  as  the  Spirophyton 
cauda-Galli)  are  common  in  some  of  the  marine  strata  ;  whilst  coal, 
according  to  the  researches  of  the  Abbe  Castracane,  is  asserted  commonly 
to  contain  the  siliceous  envelopes  of  Diatoms. 


THE  CARBONIFEROUS   PERIOD. 


165 


which  date  from  the  Devonian.     The  simply  herbaceous  ferns 
are  extremely  numerous,  and  belong  to  such  widely-distributed 


Fig.  109. — Calamites  cannesformis.     Carboniferous  Rocks,  Europe  and 
North  America. 

and  largely-represented  genera  as  Neuropteris,  Odontopteris  (fig. 

1 08),  Alethopteris,  Pecopteris,  Sphenopteris,  Hymenophyllites,  &c. 

The  fossils  known  as  Calamites  (fig.  109)  are  very  common 


1 66  HISTORICAL   PALEONTOLOGY. 

in  the  Carboniferous  deposits,  and  have  given  occasion  to  an 
abundance  of  research  and  speculation.  They  present  them- 
selves as  prostrate  and  flattened  striated  stems,  or  as  similar 
uncompressed  stems  growing  in  an  erect  position,  and  some- 
times attaining  a  length  of  twenty  feet  or  more.  Externally,  the 
stems  are  longitudinally  ribbed,  with  transverse  joints  at  regular 
intervals,  these  joints  giving  origin  to  a  whorl  of  branchlets, 
which  may  or  may  not  give  origin  to  similar  whorls  of  smaller 
branchlets  still.  The  stems,  further,  were  hollow,  with  trans- 
verse partitions  at  the  joints,  and  having  neither  true  wood  nor 
bark,  but  only  a  thin  external  fibrous  shell.  There  can  be  little 
doubt  but  that  the  Catamites  are  properly  regarded  as  colossal 
representatives  of  the  little  Horse-tails  (Equisetacece)  of  the 
present  day.  They  agree  with  these  not  only  in  the  general 
details  of  their  organisation,  but  also  in  the  fact  that  the  fruit 
was  a  species  of  cone,  bearing  "spore-cases"  under  scales. 
According  to  Principal  Dawson,  the  Catamites  "  grew  in  dense 
brakes  on  the  sandy  and  muddy  flats,  subject  to  inundation, 
or  perhaps  even  in  water ;  and  they  had  the  power  of  budding 
out  from  the  base  of  the  stem,  so  as  to  form  clumps  of  plants, 
and  also  of  securing  their  foothold  by  numerous  cord-like  roots 
proceeding  from  various  heights  on  the  lower  part  of  the 
stem." 

The  Lepidodendroids,  represented  mainly  by  the  genus 
Lepidodendron  itself  (fig.  no),  were  large  tree-like  plants, 
which  attain  their  maximum  in  the  Carboniferous  period,  but 
which  appear  to  commence  in  the  Upper  Silurian,  are  well 
represented  in  the  Devonian,  and  survive  in  a  diminished  form 
into  the  Permian.  The  trunks  of  the  larger  species  of  Lepido- 
dendron at  times  reach  a  length  of  fifty  feet  and  upwards,  giv- 
ing off  branches  in  a  regular  bifurcating  manner.  The  bark 
is  marked  with  numerous  rhombic  or  oval  scars,  arranged  in 
quincunx  order,  and  indicating  the  points  where  the  long, 
needle-shaped  leaves  were  formerly  attached.  The  fruit  con- 
sisted of  cones  or  spikes,  carried  at  the  ends  of  the  branches, 
and  consisting  of  a  central  axis  surrounded  by  overlapping 
scales,  each  of  which  supports  a  "  spore-case  "  or  seed-vessel. 
These  cones  have  commonly  been  described  under  the  name 
of  Lepidostrobi.  In  the  structure  of  the  trunk  there  is  nothing 
comparable  to  what  is  found  in  existing  trees,  there  being 
a  thick  bark  surrounding  a  zone  principally  composed  of 
"scalariform"  vessels,  this  in  turn  enclosing  a  large  central  pith. 
In  their  general  appearance  the  Lepidodendra  bring  to  mind 
the  existing  Araucarian  Pines  ;  but  they  are  true  "  Crypto- 
gams," and  are  to  be  regarded  as  a  g'gantic  extinct  type  of  the 


THE   CARBONIFEROUS   PERIOD. 


I67 


modern  Club-mosses  (Lyeopodiacea).     They  are  amongst  the 
commonest   and    most    characteristic   of    the    Carboniferous 


Fig.  no. — Lepidodendron  Sternbergii,  Carboniferous,  Europe.      The   central   figrtre 
represents  a  portion  ol  tne  trunk  with  its  branches,  much  reduced  in  size.     The  right- 
hand  figure  is  a  portion  of  a  branch  with  the  leaves  partially  attached  to  it ;  and  the  left- 
hand  figure  represents  the  end  of  a  branch  bearing  a  cone  of  fructification, 
v 

plants;  and  the  majority  of  the  "spore-cases"  so  commonly 
found  in  the  coal  appear  to  have  been  derived  from  the  cones 
of  Lepidodendroids. 


1 68  HISTORICAL   PALAEONTOLOGY. 

The  so-called  Sigiltarioids,  represented  mainly  by  Sigillaria 
itself  (fig.  in),  were  no  less  abundant  and  characteristic  of  the 
Carboniferous  forests  than  the  Lepidodendra.  They  commence 
their  existence,  so  far  as  known,  in  the  Devonian  period,  but 
they  attain  their  maximum  in  the  Carboniferous  ;  and — unlike 
the  Lepidodendroids — they  are  not  known  to  occur  in  the 
Permian  period.  They  are  comparatively  gigantic  in  size, 
often  attaining  a  height  of  from  thirty  to  fifty  feet  or  more  ; 
but  though  abundant  and  well  preserved,  great  divergence  of 
opinion  prevails  as  to  their  true  affinities.  The  name  of  Sigil- 
larioids  (Lat.  sigilla,  little  seals  or  images)  is  derived  from  the 
fact  that  the  bark  is  marked  with  seal-like  impressions  or  leaf- 
scars  (fig.  in). 

Externally,  the  trunks  of  Sigillaria  present  strong  longitudinal 
ridges,  with  vertical  alternating  rows  of  oval  leaf- scars  indicating 


Fig.  in. — Fragment  of  the  external  surface  of  Sigillaria  Grcesen,  showing  the  ribs  and 
leaf-scars.  The  left-hand  figure  represents  a  small  portion  enlarged.  Carboniferous, 
Europe. 

the  points  where  the  leaves  were  originally  attached.  The  trunk 
was  furnished  with  a  large  central  pith,  a  thick  outer  bark,  and 
an  intermediate  woody  zone, — composed,  according  to  Dawson, 
partly  of  the  disc-bearing  fibres  so  characteristic  of  Conifers ; 
but,  according  to  Carruthers,  entirely  made  up  of  the  "  scalari- 
form  "  vessels  characteristic  of  Cryptogams.  The  size  of  the 
pith  was  very  great,  and  the  bark  seems  to  have  been  the  most 
durable  portion  of  the  trunk.  Thus  we  have  evidence  that 
in  many  cases  the  stumps  and  "stools"  of  Sigilfaria,  standing 


THE   CARBONIFEROUS   PERIOD.  169 

upright  in  the  old  Carboniferous  swamps,  were  completely 
hollowed  out  by  internal  decay,  till  nothing  but  an  exterior 
shell  of  bark  was  left.  Often  these  hollow  stumps  became 
ultimately  filled  up  with  sediment,  sometimes  enclosing  the 
remains  of  galley-worms,  land- snails,  or  Amphibians,  which 
formerly  found  in  the  cavity  of  the  trunk  a  congenial  home ; 
and  from  the  sandstone  or  shale  now  filling  such  trunks  some 
of  the  most  interesting  fossils  of  the  Coal-period  have  been 
obtained.  There  is  little  certainty  as  to  either  the  leaves  or 
fruits  of  SigiJfaria,  and  there  is  equally  little  certainty  as  to  the 
true  botanical  position  of  these  plants.  By  Principal  Dawson 
they  are  regarded  as  being  probably  flowering  plants  allied  to 
the  existing  "  false  palms"  or  "  Cycads  ;"  but  the  high  author- 
ity of  Mr  Carruthers  is  to  be  quoted  in  support  of  the  belief 
that  they  are  Cryptogamic,  and  most  nearly  allied  to  the  Club- 
mosses. 

Leaving  the  botanical  position  of  Sigillaria  thus  undecided, 
we  find  that  it  is  now  almost  universally  conceded  that  the 
fossils  originally  described  under  the  name  of  Stigmaria  are 
the  roots  of  Sigillaria,  the  actual  connection  between  the  two 
having  been  in  numerous  instances  demonstrated  in  an  unmis- 
takable manner.  The  Stigmaricz  (fig.  112)  ordinarily  present 
themselves  in  the  form  of  long,  compressed  or  rounded  frag- 


Fig.  112. — Stigmaria  ficoides.     Quarter  natural  size.     Carboniferous. 

ments,  the  external  surface  of  which  is  covered  with  rounded 
pits  or  shallow  tubercles,  each  of  which  has  a  little  pit  or  de- 
pression in  its  centre.  From  each  of  these  pits  there  proceeds, 
in  perfect  examples,  a  long  cylindrical  rootlet ;  but  in  many 
cases  these  have  altogether  disappeared.  In  their  internal 
structure,  Stigmaria  exhibits  a  central  pith  surrounded  by  a 
sheath  of  scalariform  vessels,  the  whole  enclosed  in  a  cellular 
envelope.  The  Stigmarice  are  generally  found  ramifying  in 


1 70  HISTORICAL    PALEONTOLOGY. 

the  "under-day,"  which  forms  the  floor  of  a  bed  of  coal,  and 
which  represents  the  ancient  soil  upon  which  the  Sigillarice  grew. 
The  Lepidodendroids  and  Sigillarioids,  though  the  first  were 
certainly,  and  the  second  possibly,  Cryptogamic  or  flowerless 
plants,  must  have  constituted  the  main  mass  of  the  forests  of 
the  Coal  period;  but  we  are  not  without  evidence  of  the  exist- 
ence at  the  same  time  of  genuine  "  trees,"  in  the  technical 
sense  of  this  term — namely,  flowering  plants  with  large  woody 
stems.  So  far  as  is  certainly  known,  all  the  true  trees  of  the 
Carboniferous  formation  were  Conifers,  allied  to  the  existing 
Pines  and  Firs.  They  are  recognised  by  the  great  size  and . 
concentric  woody  rings  of  their  prostrate,  rarely  erect  trunks, 
and  by  the  presence  of  disc-bearing  fibres  in  their  wood,  as 
demonstrated  by  the  microscope;  and  the  principal  genera 
which  have  been  recognised  are  Dadoxylon,  Palceoxyloti, 
Arancarioxylon,  and  Pinites.  Their  fruit  is  not  known  with 
absolute  certainty,  unless  it  be  represented,  as  often  conjectured, 
by  Trigonocarpon  (fig.  113).  The  fruits  known  under  this 
name  'are  nut-like,  often  of  consider- 
able size,  and  commonly  three-  or  six- 
angled.  They  probably  originally  pos- 
sessed a  fleshy  envelope ;  and  if  truly 
referable  to  the  Conifers,  they  would 
indicate  that  these  ancient  evergreens 
produced  berries  instead  of  cones, 
and  thus  resembled  the  modern  Yews 
rather  than  the  Pines.  It  seems, 
further,  that  the  great  group  of  the 
Cycads,  which  are  nearly  allied  to  the  Conifers,  and  which 
attained  such  a  striking  prominence  in  the  Secondary  period, 
probably  commenced  its  existence  during  the  Coal  period  ; 
but  these  anticipatory  forms  are  comparatively  few  in  number, 
and  for  the  most  part  of  somewhat  dubious  affinities. 


CHAPTER     XIII. 

THE   CARBONIFEROUS  PERIOD— Continued. 
ANIMAL  LIFE  OF  THE  CARBONIFEROUS. 

We  have  seen  that  there  exists  a  great  difference  as  to  the 
mode  of  origin  of  the  Carboniferous  sediments,  some  being 
purely  marine,  whilst  others  are  terrestrial;  and  others,  again, 


THE   CARBONIFEROUS    PERIOD.  I/ 1 

have  been  formed  in  inland  swamps  and  morasses,  or  in  brack- 
ish-water lagoons,  creeks,  or  estuaries.  A  corresponding  dif- 
ference exists  necessarily  in  the  animal  remains  of  these  de- 
posits, and  in  many  regions  this  difference  is  extremely  well 
marked  and  striking.  The  great  marine  limestones  which 
characterise  the  lower  portion  of  the  Carboniferous  series  in 
Britain,  Europe,  and  the  eastern  portion  of  America,  and  the 
calcareous  beds  which  are  found  high  up  in  the  Carboniferous 
in  the  western  States  of  America,  may,  and  do,  often  contain 
the  remains  of  drifted  plants  ;  but  they  are  essentially  charac- 
terised by  marine  fossils;  and,  moreover,  they  can  be  demon- 
strated by  the  microscope  to  be  almost  wholly  composed  of 
the  remains  of  animals  which  formerly  inhabited  the  ocean. 
On  the  other  hand,  the  animal  remains  of  the  beds  accompany- 
ing the  coal  are  typically  the  remains  of  air-breathing,  terres- 
trial, amphibious,  or  aerial  animals,  together  with  those  which 
inhabit  fresh  or  brackish  waters.  Marine  fossils  may  be  found 
in  the  Coal-measures,  but  they  are  invariably  confined  to  spe- 
cial horizons  in  the  strata,  and  they  indicate  temporary  depres- 
sions of  the  land  beneath  the  sea.  Whilst  the  distinction  here 
mentioned  is  one  which  cannot  fail  to  strike  the  observer,  it  is 
convenient  to  consider  the  animal  life  of  the  Carboniferous  as 
a  whole  :  and  it  is  simply  necessary,  in  so  doing,  to  remember 
that  the  marine  fossils  are  in  general  derived  from  the  inferior 
portion  of  the  system;  whilst  the  air-breathing,  fresh-water,  and 
brackish- water  forms  are  almost  exclusively  derived  from  the 
superior  portion  of  the  same. 

The  Carboniferous  Protozoans  consist  mainly  of  Foramini- 
fera  and  Sponges.  The  latter  are  still  very  insufficiently  known, 
but  the  former  are  very  abundant,  and  belong  to  very  varied 
types.  Thin  slices  of  the  limestones  of  the  period,  when  ex- 
amined by  the  microscope,  very  commonly  exhibit  the  shells 
of  Foraminifera  in  greater  or  less  plenty.  Some  limestones, 
indeed,  are  made  up  of  little  else  than  these  minute  and  elegant 
shells,  often  belonging  to  types,  such  as  the  Textularians  and 
Rotalians,  differing  little  or  not  at  all  from  those  now  in  exist- 
ence. This  is  the  case,  for  example,  with  the  Carboniferous 
Limestone  of  Spergen  Hill  in  Indiana  (fig.  114),  which  is 
almost  wholly  made  up  of  the  spiral  shells  of  a  species  of 
Endothyra.  In  the  same  way,  though  to  a  less  extent,  the 
black  Carboniferous  marbles  of  Ireland,  and  the  similar  mar- 
bles pf  Yorkshire,  the  limestones  of  the  west  of  England  and 
of  Derbyshire,  and  the  great  "  Scar  Limestones  "  of  the  north 
of  England,  contain  great  numbers  of  Foraminiferous  shells ; 
whilst  similar  organisms  commonly  occur  in  the  shale-beds 


1/2 


HISTORICAL  PALAEONTOLOGY; 


Fig.  114. — Transparent  slice  of  Carbon- 
iferous Limestone,  from  Spergen  Hill,  In- 
diana, U.S.,  showing  numerous  shells  of 
Endothyra(Rotalia),  BnLeyi  slightly  en- 
larged. (Original.) 


associated  with  the  limestones  throughout  the  Lower  Carbon- 
iferous series.  One  of  the  most  interesting  of  the  British  Car- 
boniferous forms  is  the  Sac- 
cammina  of  Mr  Henry  Brady, 
which  is  sometimes  present  in 
considerable  numbers  in  the 
limestones  of  Northumberland, 
Cumberland,  and  the  west 
of  Scotland,  and  which  is  con- 
spicuous for  the  comparatively 
large  size  of  its  spheroidal  or 
pear  -  shaped  shell  (reaching 
from  an  eighth  to  a  fifth  of  an 
inch  in  size).  More  widely  dis- 
tributed are  the  generally  spin- 
dle-shaped shells  of  Fusulina 
(fig.  115),  which  occur  in  vast 
numbers  in  the  Carboniferous 
Limestone  'of  Russia,  Arme- 
nia, the  Southern  Alps,  and 
Spain,  similar  forms  occurring  in  equal  profusion  in  the  higher 
limestones  which  are  found  in  the  Coal-measures  of  the  United 

States,  in  Ohio,  Illinois, 
Indiana,  Missouri,  &c.  Mr 
Henry  Brady,  lastly,  has 
shown  that  we  have  in  the 
Nummulina pristina  of  the 
Carboniferous  Limestone  of 
Namur  a  genuine  Nummu- 
lite,  precursor  of  the  great  and  important  family  of  the  Tertiary 
Nummulites. 

The  sub-kingdom  of  the  Ccelenterates,  so  far  as  certainly 
known,  is  represented  only  by  Corals;*  but  the  remains  of 
these  are  so  abundant  in  many  of  the  limestones  of  the  Car- 
boniferous formation  as  to  constitute  a  feature  little  or  not  at 
all  less  conspicuous  than  that  afforded  by  the  Crinoids.  As  is 
the  case  in  the  preceding  period,  the  Corals  belong,  almost 
exclusively,  to  the  groups  of  the  Rugosa  and  Tabidata;  and 
there  is  a  general  and  striking  resemblance  and  relationship 
between  the  coral-fauna  of  the  Devonian  as  a  whole,  and  that 

*  A  singular  fossil  has  been  described  by  Professor  Martin  Duncan  and 
Mr  Jenkins  from  the  Carboniferous  rocks  under  the  name  of  Palaocoryne, 
and  has  been  referred  to  the  Hydroid  Zoophytes  (Corynida).  Doubt, 
however,  has  been  thrown  by  other  observers  on  the  correctness  of  this 
reference. 


Fig.  115. — Fusulina  cylindrica,  Carbon- 
iferous Limestone,  Russia. 


THE   CARBONIFEROUS   PERIOD.  173 

of  the  Carboniferous.  Nevertheless,  there  is  an  equally  decid- 
ed and  striking  amount  of  difference  between  these  successive 
faunas,  due  to  the  fact  that  the  great  majority  of  the  Carbon- 
iferous species  are  new ;  whilst  some  of  the  most  characteristic 
Devonian  genera  have  nearly  or  quite  disappeared,  and  several 
new  genera  now  make  their  appearance  for  the  first  time. 
Thus,  the  characteristic  Devonian  types  Heliophyllum,  Pachy- 
phyllum,  Chonophyllum,  Acervnlaria,  Spongophyllum,  Smithia, 
Endophyllum,  and  Cystiphyllum,  have  now  disappeared;  and 
the  great  masses  of  Favosites  which  are  such  a  striking  feature  in 
the  Devonian  limestones,  are  represented  but  by  one  or  two 
degenerate  and  puny  successors.  On  the  other  hand,  we  meet 
in  the  Carboniferous  rocks  not  only  with  entirely  new  genera — 
such  as  Axophyllum,  Lophophyllum,  and  Londsdaleia — but  we 
have  an  enormous  expansion  of  certain  types  which  had  just 
begun  to  exist  in  the  preceding  period.  This  is  especially 
well  seen  in  the  case  of  the  genus  Lithostrotion  (fig.  116,  b], 
which  more  than  any  other  may  be  considered  as  the  predo- 
minant Carboniferous  group  of  Corals.  All  the  species  of 
Lithostrotion  are  compound,  consisting  either  of  bundles  of 
loosely-approximated  cylindrical  stems,  or  of  similar  "coral- 
lites"  closely  aggregated  together  into  astraeiform  colonies,  and 
rendered  polygonal  by  mutual  pressure.  This  genus  has  a 
historical  interest,  as  having  been  noticed  as  early  as  in  the 
year  1699  by  Edward  Lhwyd;  and  it  is  geologically  important 
from  its  wide  distribution  in  the  Carboniferous  rocks  of  both 
the  Old  and  New  Worlds.  Many  species  are  known,  and  whole 
beds  of  limestone  are  often  found  to  be  composed  of  little  else 
than  the  skeletons  of  these  ancient  corals,  still  standing  upright 
as  they  grew.  Hardly  less  characteristic  of  the  Carboniferous 
than  the  above  is  the  great  group  of  simple  "  cup-corals,"  of 
which  Clisiophyllum  is  the  central  type.  Amongst  types  which 
commenced  in  the  Silurian  and  Devonian,  but  which  are  still 
well  represented  here,  may  be  mentioned  Syringopora  (fig.  116, 
<?),  with  its  colonies  of  delicate  cylindrical  tubes  united  at  in- 
tervals by  cross-bars;  Zaphrentis  (fig.  116,  d\  with  its  cup- 
shaped  skeleton  and  the  well-marked  depression  (or  "fossula") 
on  one  side  of  the  calice  ;  Amplexus  (fig.  116,  c\  with  its 
cylindrical,  often  irregularly  swollen  coral  and  short  septa; 
Cyathophyllum  (fig.  1 1 6,  a},  sometimes  simple,  sometimes  form- 
ing great  masses  of  star-like  corallites ;  and  Chatetes,  with  its 
branched  stems,  and  its  minute,  ''tabulate"  tubes  (fig.  u6,/). 
The  above,  together  with  other  and  hardly  less  characteristic 
forms,  combine  to  constitute  a  coral-fauna  which  is  not  only  in 
itself  perfectly  distinctive,  but  which  is  of  especial  interest, 
13 


1/4  HISTORICAL   PAL/EON TOLOGY. 

from  the  fact  that  almost  all  the  varied  types  of  which  it  is 
composed  disappeared  utterly  before  the  close  of  the  Carbon- 


Fig.  116.— Corals  of  the  Carboniferous  Limestone,  a.  Cyathophyllum  paracida,  show- 
ing young  corallites  budded  forth  from  the  disc  of  the  old  one  ;  a1 ',  One  of  the  corallites 
of  the  same,  seen  in  cross-section;  b,  Fragment  of  a  mass  of  Litliostrotion  irregulars; 
/'',  One  of  the  corallites  of  the  same,  divided  transversely  ;  c,  Portion  of  the  simple  cylin- 
drical coral  of  Amplexus  cornlloides  I  d ',  Transverse  section  of  the  same  species;  d, 
Zaphreiitis  vermicularis,  showing  the  depression  or  "fossula"  on  one  side  of  the  cup; 
e.  Fragment  of  a  mass  of  Syringopora  ramulosa',  f,  Fragment  of  Chcetetes  tumidus;  _/', 
Portion  of  the  surface  of  the  same,  enlarged.  From  the  Carboniferous  Limestone  of 
Britain  and  Belgium.  (After  Thomson,  De  Koninck,  Milne-Edwards  and  Haime,  and 
the  Author.) 


iferous  period.  In  the  first  marine  sediments  of  a  calcareous 
nature  which  succeeded  to  the  Coal-measures  (the  magnesian 
limestones  of  the  Permian),  the  great  group  of  the  Rugose 
corals,  which  flourished  so  largely  throughout  the  Silurian,  De- 
vonian, and  Carboniferous  periods,  is  found  to  have  all  but 


THE   CARBONIFEROUS    PERIOD. 


175 


disappeared,  and  it  is  never  again  represented  save  sporadi- 
cally and  by  isolated  forms. 

Amongst  the  Echinoderms,  by  far  the  most  important  forms 
are  the  Sea-lilies  and  the  Sea-urchins— the  former  from  their 
great  abundance,  and  the  latter  from  their  singular  structure ; 
but  the  little  group  of  the  "  Pentremites  "  also  requires  to  be 
noticed.  The  Sea-lilies  are  so  abundant  in  the  Carboniferous 
rocks,  that  it  has  been  proposed  to  call  the  earlier  portion  of 
the  period  the  "Age  of  Crinoids."  Vast  masses  of  the  lime- 
stones of  the  period  are  "  crinoidal,"  being  more  or  less  ex- 
tensively composed  of  the  broken  columns,  and  detached  plates 
and  joints  of  Sea-lilies,  whilst  perfect  "  heads  "  may  be  exceed- 
ingly rare  and  difficult  to  procure.  In  North  America  the  re- 
mains of  Crinoids  are  even  more  abundant  at  this  horizon  than 
in  Britain,  and  the  specimens  found  seem  to  be  commonly 
more  perfect.  The  commonest  of  the  Carboniferous  Crinoids 
belong  to  the  genera  Cyathocrinust  Actinocrinus,  Platycrinus, 


Fig.  117. — Platycrinus  tricontadactylus,  Lower  Carboniferous.  The  left-hand  figure 
shows  the  calyx,  arm-',  and  upper  part  of  the  stem  ;  and  the  figure  next  this  shows  the  sur- 
face of  one  of  the  joints  of  the  column.  The  right-hand  figure  shows  the  proboscis.  (After 
M'Coy.) 

(fig.  117),  Poteriocrinus,  Zeacrinus,  and  Forbesiocrinus.    Closely 
allied  to  the  Crinoids,  or  forming  a  kind  of  transition  between 


176 


HISTORICAL   PALEONTOLOGY. 


these  and  the  Cystideans,  is  the  little  group  of  the  "  Pentre- 
mites,"  or  Blastoids  (fig.  118).     This  group  is  first  known  to 


Fig.  118. — A,  Pentremites  pyriformis>  side-view  of  the  body  ("calyx")  ;  B,  The  same 
viewed  from  below,  showing  the  arrangement  of  the  plates  ;  C,  Body  of  Pentrenutes 
ccnoideus,  viewed  from  above.  Carboniferous. 

have  commenced  its  existence  in  the  Upper  Silurian,  and  it 
increased  considerably  in  numbers  in  the  Devonian  ;  but  it 
was  in  the  seas  of  the  Carboniferous  period  that  it  attained  its 
maximum,  and  no  certain  representative  of  the  family  has  been 
detected  in  any  later  deposits.  The  "  Pentremites  "  resemble 
the  Crinoids  in  having  a  cup-shaped  body  (fig.  118,  A)  enclosed 
by  closely-fitting  calcareous  plates,  and  supported  on  a  short 
stem  or  "  column,"  composed  of  numerous  calcareous  pieces 
flexibly  articulated  together.  They  differ  from  the  Crinoids, 
however,  in  the  fact  that  the  upper  surface  of  the  body  does 
not  support  the  crown  of  branched  feathery  "  arms/'  which  are 
so  characteristic  of  the  latter.  On  the  contrary,  the  summit  of 
the  cup  is  closed  up  in  the  fashion  of  a  flower-bud,  whence  the 
technical  name  of  Blastoidea  applied  to  the  group  (Gr.  blastos, 
a  bud ;  eidos,  form).  From  the  top  of  the  cup  radiate  five  broad, 
transversely-striated  areas  (fig.  118,  C).  each  with  a  longitudi- 
nal groove  down  its  middle;  and  along  each  side  of  each  of 


THE  CARBONIFEROUS   PERIOD.  177 

these  grooves  there   seems  to  have  been  attached  a  row  of 
short  jointed  calcareous  filaments  or  "  pinnules." 

A  few  Star-fishes  and  Brittle-stars  are  known  to  occur  in  the 
Carboniferous  rocks ;  but  the  only  other  Echinoderms  of  this 
period  which  need  be  noticed  are  the  Sea-urchins  (Echinoid$). 
Detached  plates  and  spines  of  these  are  far  from  rare  in  the 
Carboniferous  deposits  \  but  anything  like  perfect  specimens 
are  exceedingly  scarce.  The  Carboniferous  Sea-urchins  agree 
with  those  of  the  present  day  in  having  the  body  enclosed  in 
a  shell,  formed  by  an  enormous  number  of  calcareous  plates 
articulated  together.  The  shell  may  be  regarded  as,  typically, 
nearly  spherical  in  shape,  with  the  mouth  in  the  centre  of  the 
base,  and  the  excretory  opening  or  vent  at  its  summit.  In  both 
the  ancient  forms  and  the  recent  ones,  the  plates  of  the  shell 


Fig.  119. — PaZtzckinus  ellipticns,  one  of  the  Carboniferous  Sea-urchins.  Tlte  left- 
hand  figure  shows  one  of  the  "ambulacral  areas "  enlarged,  exhibiting  the  perforated 
plates.  The  right-}  and  figure  exhibits  a  single  plate  from  one  of  the  "inter-ambtilacral 
areas."  (After  M'Coy.) 

are  arranged  in  ten  zones  which  generally  radiate  from  the 
summit  to  the  centre  of  the  base.  In  five  of  these  zones — 
termed  the  "  ambulacral  areas  " — the  plates  are  perforated  by 
minute  apertures  or  "  pores,"  through  which  the  animal  can 
protrude  the  little  water-tubes  ("  tube-feet ")  by  which  its  loco- 
motion is  carried  on.  In  the  other  five  zones — the  so-called 
" inter-ambulacral  areas"  —the  plates  are  of  larger  size,  and 
are  not  perforated  by  any  apertures.  In  all  the  modern  Sea- 
urchins  each  of  these  ten  zones,  whether  perforate  or  imper- 
forate,  is  composed  of  two  rows  of  plates ;  and  there  are  thus 
twenty  rows  of  plates  in  all.  In  the  Palaeozoic  Sea-urchins,  on 
the  other  hand,  the  "ambulacral  areas"  are  often  like  those 
of  recent  forms,  in  consisting  of  two  rows  of  perforated  plates 
(fig.  119);  but  the  "inter-ambulacral  areas  "are  always  quite 


1/8  HISTORICAL  PALEONTOLOGY. 

peculiar  in  consisting  each  of  three,  four,  five,  or  more  rows  of 
large  imperforate  plates,  whilst  there  are  sometimes  four  or  ten 
rows  of  plates  in  the  "  ambulacral  areas  "  also :  so  that  there 
are  many  more  than  twenty  rows  of  plates  in  the  entire  shell. 
Some  of  the  Palaeozoic  Sea-urchins,  also,  exhibit  a  very  pecu- 
liar singularity  of  structure  which  is  only  known  to  exist  in  a 
very  few  recently-discovered  modern  forms  (viz.,  Calveria  and 
Phormosoma).  The  plates  of  the  inter  -  ambulacral  areas, 
namely,  overlap  one  another  in  an  imbricating  manner,  so  as 
to  communicate  a  certain  amount  of  flexibility  to  the  shell ; 
whereas  in  the  ordinary  living  forms  these  plates  are  firmly 
articulated  together  by  their  edges,  and  the  shell  forms  a  rigid 
immovable  box.  The  Carboniferous  Sea-urchins  which  ex- 
hibit this  extraordinary  peculiarity  belong  to  the  genera  Lepi- 
dechinus  and  Lepidesthes,  and  it  seems  tolerably  certain  that 
a  similar  flexibility  of  the  shell  existed  to  a  less  degree  in 
the  much  more  abundant  genus  Arch&oddaris.  The  Carbon- 
iferous Sea-urchins,  like  the  modern  ones,  possessed  movable 
spines  of  greater  or  less  length,  articulated  to  the  exterior  of 
the  shell ;  and  these  structures  are  of  very  common  occur- 
rence in  a  detached  condition.  The  most  abundant  genera 
are  Archaocidaris  and  Pal&chinus ;  but  the  characteristic 
American  forms  belong  principally  to  Melonitcs,  Oligoporus, 
and  Lepidechinus. 

Amongst  the  Annelides  it  is  only  necessary  to  notice  the  little 
spiral   tubes  of  Spirorbis   Carbonarius  (fig.    120),  which   are 


Fig.  120. — Spirorbis  (Microconckus)  Carbonarius,  of  the  natural  size,  attached  to  a  fossil 
plant,  and  magnified.     Carboniferous  .Britain  and  North  America.     (After  Davvson.) 

commonly  found  attached  to  the  leaves  or  stems  of  the  Coal- 
plants.  This  fact  shows  that  though  the  modern  species  of 
Spirorbis  are  inhabitants  of  the  sea,  these  old  representatives 
of  the  genus  must  have  been  capable  of  living  in  the  brackish 
waters  of  lagoons  and  estuaries. 

The  Crustaceans  of  the  Carboniferous  rocks  are  numerous, 


THE   CARBONIFEROUS   PERIOD. 


179 


and  belong  partly  to  structural  types  with  which  we  are  already 
familiar,  and  partly  to  higher  groups  which  come  into  existence 
here  for  the  first  time.  The  gigantic  Eurypterids  of  the  Upper 
Silurian  and  Devonian  are  but  feebly  represented,  and  make 
their  final  exit  here  from  the  scene  of  life.  Their  place,  how- 
ever, is  taken  by  peculiar  forms  belonging  to  the  allied  group 
of  the  Xiphosura,  represented  at  the  present  day  by  the  King- 
crabs  or  "  Horse-shoe  Crabs  "  (Limulus).  Characteristic  forms 
of  this  group  appear  in  the  Coal-measures  both  of  Europe  and 
America ;  and  though  constituting  three  distinct  genera  (Prest- 
wic/iia,  BelinuruS)  and  Euproops\  they  are  all  nearly  related 
to  one  another.  The  best  known  of  them,  perhaps,  is  the 
Prestwichia  rotundata  of  Coalbrookdale,  here  figured  (fig. 
The  ancient  and  for- 
merly powerful  order 
of  the  Trilobites  also 
undergoes  its  final  ex- 
tinction here,  not  sur- 
viving the  deposition 
of  the  Carboniferous 
Limestone  series  in  Eu- 
rope, but  extending  its 
range  in  America  into 
the  Coal-measures.  All 
the  known  Carbonifer- 
ous forms  are  small  in 
size  and  degraded  in 
point  of  structure,  and 
they  are  referable  to 
but  three  genera  (Phil- 

UpSia,   GriffithideS,    and  Fig.  r-z-i.—Prestwchia    rotundata,     a     Lirr.nloid 

Brachymetopus],  be-  wSSSScL)  Coal-measures'  Britain'  <A^  Henry 
longing  to  a  single  fa- 
mily. The  Phillipsia  seminifera  here  figured  (fig.  122,  a)  is  a 
characteristic  species  in  the  Old  World.  The  AVater- fleas 
(Ostracoaa)  are  extremely  abundant  in  the  Carboniferous  rocks, 
whole  strata  being  often  made  up  of  little  else  than  the  little 
bivalved  shells  of  these  Crustaceans.  Many  of  them  are  ex- 
tremely small,  averaging  about  the  size  of  a  millet-seed ;  but  a 
few  forms,  such  as  Entomoconchus  Scouleri  (fig.  122,  c),  may  attain 
a  length  of  from  one  to  three  quarters  of  an  inch.  The  old 
group  of  the  Phyllopods  is  likewise  still  represented  in  some 
abundance,  partly  by  tailed  forms  of  a  shrimp-like  appearance, 
such  as  Dithyrocaris  (fig.  122,  </),  and  partly  by  the  curious 
striated  Estheria  and  their  allies,  which  present  a  curious 


t8o 


HISTORICAL   PALEONTOLOGY. 


resemblance  to  the  true  Bivalve  Molluscs  (fig.  122,^).  Lastly, 
we  meet  for  the  first  time  in  the  Carboniferous  rocks  with  the 
remains  of  the  highest  of  all  the  groups  of  Crustaceans — name- 
ly, the  so-called  "  Decapods,"  in  which  there  are  five  pairs  of 
walking-limbs,  and  the  hinder  end  of  the  body  ("  abdomen  ") 
is  composed  of  separate  rings,  whilst  the  anterior  end  is  cov- 
ered by  a  head-shield  or  "  carapace."  All  the  Carboniferous 
Decapods  hitherto  discovered  resemble  the  existing  Lobsters, 


Fig.  122. — Crustaceans  of  the  Carboniferous  Rocks,  a,  Ph>llips;a  setninifera,  of  the 
natural  size — Mountain  Limestone,  Europe;  b,  One  valve  of  the  shell  of  Estheria  tenella, 
of  the  natural  size  and  enlarged — Coal-measures,  Europe  ;  c,  Bivalved  shell  of  Entomo- 
conchus  Scouleri,  of  the  natural  size — Mountain  Limestone,  Europe  ;  d,  Dithyrocaris 
Scouleri,  reduced  in  size — Mountain  Limestone,  Ireland  ;  e,  Paleeocaris  typus,  slightly 
enlarged — Coal-measures,  North  America ;  f,  Anthrapalcemon  gracilis,  of  the  natural 
size — Coal-measures,  North  America.  (After  De  Koninck,  M'Coy,  Rupert  Jones,  and 
Meek  and  Worthen.) 

Prawns,  and  Shrimps  (the  Macrura],  in  having  a  long  and  well- 
developed  abdomen  terminated  by  an  expanded  tail-fin.  The 
Palczocaris  typus  (fig.  122,  e]  and  the  Anthrapalcemon  gracilis 
(fig.  122, /),  from  the  Coal-measures  of  Illinois,  are  two  of  the 
best  understood  and  most  perfectly  preserved  of  the  few  known 
representatives  of  the  "  Long-tailed  "  Decapods  in  the  Car- 
boniferous series.  The  group  of  the  Crabs  or  "  Short-tailed  " 


THE  CARBONIFEROUS   PERIOD.  l8l 

Decapods  (Brachyura\  in  which  the  abdomen  is  short,  not 
terminated  by  a  tail-fin,  and  tucked  away  out  of  sight  beneath 
the  body,  is  at  present  not  known  to  be  represented  at  all  in 
the  Carboniferous  deposits. 

In  addition  to  the  water-inhabiting  group  of  the  Crustaceans, 
we  find  the  articulate  animals  to  be  represented  by  members 
belonging  to  the  air-breathing  classes  of  the  Arachnida,  Myria- 
poda, an.l  Insecta.  The  remains  of  these,  as  might  have  been 
expected,  are  not  known  to  occur  in  the  marine  limestones  of 
the  Carboniferous  series,  but  are  exclusively  found  in  beds  asso- 
ciated with  the  Coal,  which  have  been  deposited  in  lagoons, 
estuaries,  or  marshes,  in  the  immediate  vicinity  of  the  land,  and 
which  actually  represent  an  old  land-surface.  The  Arachnids 
are  at  present  the  oldest  known  of  their  class,  and  are  repre- 
sented both  by  true  Spiders  and  Scorpions.  Remains  of  the 
latter  (fig.  123)  have  been  found  both  in  the  Old  and  New 


Fig.  -L^.—Cyclophthalmus  senior.     A  fossil  Scorpion  from  the  Coal-measures 
of  Bohemia. 

Worlds,  and  indicate  the  existence  in  the  Carboniferous  period 
of  Scorpions  differing  but  very  little  from  existing  forms.  The 
group  of  the  Myriapoda,  including  the  recent  Centipedes  and 
Galley-worms,  is  likewise  represented  in  the  Carboniferous  strata, 


182 


HISTORICAL   PALEONTOLOGY. 


but  by  forms  in  many  respects  very  unlike  any  that  are  known 
to  exist  at  the  present  day.  The  most  interesting  of  these 
were  obtained  by  Principal  Dawson,  along  with  the  bones  of 
Amphibians  and  the  shells  of  Land-snails,  in  the  sediment  filling 
the  hollow  trunks  of  Sigillaria,  and  they  belong  to  the  genera 
Xylobius  (fig.  124)  and  Archiulus.  Lastly,  the  true  insects  are 


Fig.  124. — Xylobius  Sigillarice,  a  Carboniferous  Myriapod.  a,  A  specimen,  of  the 
natural  size;  b,  Anterior  portion  of  the  same,  enlarged  ;  c,  Posterior  portion,  enlarged. 
From  the  Coal-measures  of  Nova  Scotia.  (After  Dawson.) 

represented  by  various  forms  of  Beetles  (Coleoptera),  Orthoptera 
(such  as  Cockroaches),  and  Neuropterous  insects  resembling 
those  which  we  have  seen  to  have  existed  towards  the  close  of 


Fig.  125. — Haplophlebium  Earnest,  a  Carboniferous  insect,  from  the  Coal-measures 
of  Nova  Scotia.     (After  Dawson.) 

the  Devonian  period.     One  of  the  most  remarkable  of  the 
latter  is  a  huge  May-fly  (Haplophlebium  Earnest,  fig.  125),  with 


THE   CARBONIFEROUS   PERIOD. 


183 


netted  wings  attaining  an  expanse  of  fully  seven  inches,  and 
therefore  much  exceeding  any  existing  Ephemerid  in  point 
of  size. 

The  lower  groups  of  the  Mollusca  are  abundantly  represented 
in  the  marine  strata  of  the  Carboniferous  series  by  Polyzoans 


Fig.  126. — Carboniferous  Polyzoa.  a,  Fragment  of  Polyfiora  dendroides,  of  the  natural 
size,  Ireland  ;  a'  Small  portion  of  the  same,  enlarged  to  show  the  cells  ;  b,  Glauconome 
pulckerrima,  a  fragment,  of  the  natural  size,  Ireland  ;  b',  Portion  of  the  same,  enlarged  ; 
c,  The  central  screw-like  axis  ot  Archimedes  Wortheni,  of  the  natural  size — Carboniferous, 
America  ;  c1,  Portion  of  the  exterior  of  the  frond  of  the  same,  enlarged  ;  c",  Portion  of 
the  interior  of  the  frond  of  the  same  showing  the  mouths  of  the  cells,  enlarged.  (After 
M 'Coy  and  Hall.) 

and  Brachiopods.  Amongst  the  former,  although  a  variety  of 
other  types  are  known,  the  majority  still  belong  to  the  old 
group  of  the  "  Lace-corals  "  (Fenestellid(E\  some  of  the  charac- 
teristic forms  of  which  are  here  figured  (fig.  1 26).  The  graceful 


1-84  HISTORICAL  PALEONTOLOGY. 

netted  fronds  of  Fenestella,  Retepora,  and  Polypora  (fig.  126,  a) 
are  highly  characteristic,  as  are  the  slender  toothed  branches 
of  Glauconome  (fig.  126,  b\  A  more  singular  form,  however,  is 
the  curious  Archimedes  (fig.  126,  <:),  which  is  so  characteristic 
of  the  Carboniferous  formation  of  North  America.  In  this  re- 
markable type,  the  colony  consists  of  a  succession  of  funnel- 
shaped  fronds,  essentially  similar  to  Fencstella  in  their  structure, 
springing  in  a  continuous  spiral  from  a  strong  screw-like  vertical 
axis.  The  outside  of  the  fronds  is  simply  striated;  but  the 
branches  exhibit  on  the  interior  the  mouths  of  the  little  cells 
in  which  the  semi-independent  beings  composing  the  colony 
originally  lived. 

The  Brachiopods  are  extremely  abundant,  and  for  the  most 
part  belong  to  types  which  are  exclusively  or  principally 
Palaeozoic  in  their  range.  The  old  genera  Strophomcna,  Orthis 
(fig.  127,  c\  Athyris(h<g.  127,  e),  Rhynchonella  (fig.  127,  g\  and 
Spirifera  (fig.  127,  h\  are  still  well  represented — the  latter,  in 
particular,  existing  under  numerous  specific  forms,  conspicuous 
by  their  abundance  and  sometimes  by  their  size.  Along  with 
these  ancient  groups,  we  have  representatives — for  the  first  time 
in  any  plenty — of  the  great  genus  Terebratula  (fig.  127,  d), 
which  underwent  a  great  expansion  during  later  periods,  and 
still  exists  at  the  present  day.  The  most  characteristic  Car- 
boniferous Brachiopods,  however,  belong  to  the  family  of  the 
Productida,  of  which  the  principal  genus  is  Producta  itself. 
This  family  commenced  its  existence  in  the  Upper  Silurian 
with  the  genus  Chomtes,  distinguished  by  its  spinose  hinge- 
margin.  This  genus  lived  through  the  Devonian,  and  flourished 
in  the  Carboniferous  (fig.  i2j,f).  The  genus  Producta  itself, 
represented  in  the  Devonian  by  the  nearly  allied  Productella, 
appeared  first  in  the  Carboniferous,  at  any  rate  in  force,  a"nd 
survived  into  the  Permian  ;  but  no  member  of  this  extensive 
family  has  yet  been  shown  to  have  over-lived  the  Palaeozoic 
period.  The  Producta  of  the  Carboniferous  are  not  only  ex- 
ceedingly abundant,  but  they  have  in  many  instances  a  most 
extensive  geographical  range,  and  some  species  attain  what 
may  fairly  be  considered  gigantic  dimensions.  The  shell  (fig. 
127,  a  and  /;)  is  generally  more  or  less  semicircular,  with  a 
straight  hinge  margin,  and  having  its  lateral  angles  produced 
into  larger  or  smaller  ears  (hence  its  generic  name — "cochlea 
producta"\  One  valve  (the  ventral)  is  usually  strongly  convex, 
whilst  the  other  (the  dorsal)  is  flat  or  concave,  the  surface  of 
both  being  adorned  with  radiating  ribs,  and  with  hollow 
tubular  spines,  often  of  great  length.  The  valves  are  not 
locked  together  by  teeth,  and  there  is  no  sign  in  the  fully- 


THE  CARBONIFEROUS   PERIOD. 


I85 


grown  shell  of  an  opening  in  or  between  the  valves  for  the 
emission  of  a  muscular  stalk  for  the  attachment  of  the  shell  to 
foreign  objects.  It  is  probable,  therefore,  that  the  Products, 
unlike  the  ordinary  Lamp-shells,  lived  an  independent  exist- 
ence, their  long  spines  apparently  serving  to  anchor  them 
firmly  in  the  mud  or  ooze  of  the  sea-bottom  ;  but  Mr  Robert 
Etheridge,  jun.,  has  recently  shown  that  in  one  species  the 


Fig.  127. — Carboniferous  Brachiopoda.  a,  Producta  semireticulata,  showing  the 
slightly  concave  dorsal  valve ;  a'  Side  view  of  the  same,  showing  the  convex  ventral 
valve;  b,  Prodncta  longispina;  c,  Orthis  resupinat*  ;  d,  Terebratula  hastata ',  e, 
A  thyris  subtilita  ',  f,  Chonetes  Hardrensis  ',  g,  Rhynchonella  pleurodon  ;  A,  Spirifera 
trigonalis.  Most  of  these  forms  are  widely  distributed  in  the  Carboniferous  Limestone 
of  Britain,  Europe,  America,  &c.  All  the  figures  are  of  the  natural  size.  (After  David- 
son, De  Koninck,  and  Meek.) 

spines  were  actually  employed  as  organs  of  adhesion,  whereby 
the  shell  was  permanently  attached  to  some  extraneous  object, 
such  as  the  stem  of  a  Crinoid.  The  two  species  here  figured 
are  interesting  for  their  extraordinarily  extensive  geographical 
range — Produda  semireticulata  (fig.  127,  a)  being  found  in  the 
Carboniferous  rocks  of  Britain,  the  continent  of  Europe, 
Central  Asia,  China,  India,  Australia,  Spitzbergen,  and  North 


1 86 


HISTORICAL   PALEONTOLOGY. 


and  South  America;  whilst  P.   longispina  (fig.    127,  /;)  lias  a 
distribution  little  if  at  all  less  wide. 

The  higher  Mollusca  are  abundantly  represented  in  the 
Carboniferous  rocks  by  Bivalves  (Lamellibranchs),  Univalves 
{Gasteropoda},  Winged- snails  (Pteropoda\  and  Cephalopods. 
Amongst  the  Bivalves  we  may  note  the  great  abundance  of 
Scallops  (Aviculo/yecten  and  other  allied  forms),  together  with 
numerous  other  types — some  of  ancient  origin,  others  repre- 
sented here  for  the  first  time.  Amongst  the  Gasteropods,  \ve 
find  the  characteristically  Palaeozoic  genera  Macrocheilus  and 
Loxojiema^  the  almost  exclusively  Palaeozoic  Euomphalus,  and 
the  persistent  genus  Pleurotomaria ;  whilst  the  free-swimming 
Univalves  (ffd*ropoda)*xz  represented  by Bellerophon  '&t\&Porcel- 
lia,  and  the  Pteropoda  by  the  old  genus  Comilaria.  With  regard 
to  the  Carboniferous  Univalves,  it  is  also  of  interest  to  note  here 
the  first  appearance  of  true  air-breathing  or  terrestrial  Molluscs, 
as  discovered  by  Dawson  and  Bradley  in  the  Coal-measures  of 
Nova  Scotia  and  Illinois.  Some  of  these  ( Conuhis  priscus)  are 
true  Land-snails,  resembling  the  existing  Zonites  ;  whilst  others 
(Pupa  vetusta,  fig.  128)  appear  to  be  generically  inseparable 

from  the  "  Chrysalis- shells  " 
(Pupa)  of  the  present  day. 
All  the  known  forms — three 
in  number — are  of  small  size, 
and  appear  to  have  been  local 
in  their  distribution  or  in  their 
preservation.  More  import- 
ant, however,  than  any  of  the 
preceding,  are  the  Cephalo- 
poda, represented,  as  before, 
exclusively  by  the  chambered 
shells  of  the  Tetrabranchiates. 
The  older  and  simpler  type  of 
these,  with  simple  plain  septa,, 
and  mostly  a  central  siphuncle, 
is  represented  by  the  straight 
conical  shells  of  the  ancient 
genus  Orthoceras,  and  the  bow- 
shaped  shells  of  the  equally 
ancient  Cyrtoceras  —  some  of 
the  former  attaining  a  great  size. 
The  spirally-curved  discoidal 
shells  of  the  persistent  genus  Nautilus  are  also  not  unknown, 
and  some  of  these  likewise  exhibit  very  considerable  dimen- 
sions. Lastly,  the  more  complex  family  of  the  Ammonitid^ 


Fig.  \-2&.—Pnpa  (Dendropupa)vetusta, 
a  Carboniferous  Land-snaii  from  the  Coal- 
measures  of  Nova  Scotia,  a,  The  shell,  of 
the  natural  size ;  b,  The  same,  magnified  ; 
c,  Apex  of  the  shell,  enlarged  ;  d,  Portion 
of  the  surface,  enlarged.  (After  Dawson. ) 


THE   CARBONIFEROUS    PERIOD. 


I87 


with  lobed  or  angulated  septa,  and  a  dorsally- placed  siphuncle 
(situated  on  the  convex  side  of  the  curved  shells),  now  for  the 
first  time  commences  to  acquire  a  considerable  prominence. 
The  principal  representative  of  this  group  is  the  genus  Gonia- 
tites (fig.  129),  which  commenced  its  existence  in  the  Upper 
Silurian,  is  well  represented  in  the  De- 
vonian, and  attains  its  maximum  here. 
In  this  genus,  the  shell  is  spirally 
curved,  the  septa  are  strongly  lobed 
or  angulated,-  though  not  elaborately 
frilled  as  in  the  Ammonites,  and  the 
siphuncle  is  dorsal.  In  addition  to 
Goniatites,  the  shells  of  true  Ammon- 
ites, so  characteristic  of  the  Secondary 
period,  have  been  described  by  Dr 
Waagen  as  occurring  in  the  Carbon- 
iferous rocks  of  India. 


Fig.  129. — Goniatites  (Aganides)  JosstP.     Carboniferous  Limestone. 

Coming  finally  to  the  Vertebrata,  we  have  in  the  first  place 
to  very  briefly  consider  the  Carboniferous  fishes.  These  are 
numerous ;  but,  with  the  exception  of  the  still  dubious  "  Cono- 
donts/'  belong  wholly  to  the  groups  of  the  Ganoids  and  the 
Placoids  (including  under  the  former  head  remains  which  per- 
haps are  truly  referable  to  the  group  of  the  Dipnoi  or  Mud- 
fishes). Amongst  the  Ganoids,  the  singular  buckler-headed 
fishes  of  the  Upper  Silurian  and  Devonian  ( Cephalaspidce]  have 


1 88  HISTORICAL   PALEONTOLOGY. 

apparently  disappeared ;  and  the  principal  types  of  the  Car- 
boniferous belong  to  the  groups  respectively  represented  at 
the  present  day  by  the  Gar-pike  (Lepidosteus]  of  the  North 
American  lakes,  and  the  Polypterus  of  the  rivers  of  Africa.  Of 
the  former,  the  genera  Palceoniscus  and  Amblypterus  (fig.  130), 


Fig.  130. — Amblyfterus  macropterus.     Carboniferous. 

with  their  small  rhomboidal  and  enamelled  scales,  and  their 
strongly  unsymmetrical  tails,  are  perhaps  the  most  abundant. 
Of  the  latter,  the  most  important  are  species  belonging  to 
the  genera  Megalichthys  and  Rhizodus,  comprising  large  fishes, 
with  rhomboidal  scales,  unsymmetrical  ("  heterocercal ")  tails, 
and  powerful  conical  teeth.  These  fishes  are  sometimes  said 
to  be  "  sauroid,"  from  their  presenting  some  Reptilian  features 
in  their  organisation,  and  they  must  have  been  the  scourges 
of  the  Carboniferous  seas.  The  remains  vi.Placoid  fishes  in 
the  Carboniferous  strata  are  very  numerous,  but  consist  wholly 
of  teeth  and  fin-spines,  referable  to  forms  more  or  less  closely 
allied  to  our  existing  Port  Jackson  Sharks,  Dog-fishes,  and 
Rays.  The  teeth  are  of  very  various  shapes  and  sizes, — some 
with  sharp,  cutting  edges  (Petalodus,  Cladodus,  &c.) ;  others  in 
the  form  of  broad  crushing  plates,  adapted,  like  the  teeth  of  the 
existing  Port  Jackson  Shark  (Cestradon  Philippi\  for  breaking 
down  the  hard  shells  of  Molluscs  and  Crustaceans.  Amongst 
the  many  kinds  of  these  latter,  the  teeth  of  Psammodus  and 
Cochliodus  (fig.  131)  may  be  mentioned  as  specially  charac- 
teristic. The  fin-spines  are  mostly  similar  to  those  so  common 
in  the  Devonian  deposits,  consisting  of  hollow  defensive  spines 
implanted  in  front  of  the  pectoral  or  other  fins,  usually  slightly 
curved,  often  superficially  ribbed  or  sculptured,  and  not  un- 
commonly serrated  or  toothed.  The  genera  Ctenacanthiis, 
Gyr acanthus,  HomacantJms,  &c.,  have  been  founded  for  the 
reception  of  these  defensive  weapons,  some  of  which  indicate 
fishes  of  great  size  and  predaceous  habits. 


THE   CARBONIFEROUS   PERIOD.  189 

In  the  Devonian  rocks  we  meet  with  no  other  remains  of 
Vertebrated  animals  save  fishes  only ;  but  the  Carboniferous 
deposits  have  yielded  re- 
mains of  the  higher  group 
of  the  Amphibians.  This 
class,  comprising  our  ex- 
isting Frogs,  Toads,  and 
Newts,  stands  to  some  ex- 
tent in  a  position  midway 
between  the  class  of  the 
fishes  and  that  of  the  true 
reptiles,  being  distinguished 
from  the  latter  by  the  fact  Fig.  I3I._Teeth  of  Cochiwd™  contort™. 

that  itS  members    invariably  Carboniferous  Limestone,  Britain. 

possess   gills  in  their  early 

condition,  if  not  throughout  life;  whilst  they  are  separated  from 
the  former  by  always  possessing  true  lungs  when  adult,  and 
by  the  fact  that  the  limbs  (when  present  at  all)  are  never  in 
the  form  of  fins.  The  Amphibians,  therefore,  are  all  water- 
breathers  when  young,  and  have  respiratory  organs  adapted 
for  an  aquatic  mode  of  life ;  whereas,  when  grown  up,  they 
develop  lungs,  and  with  these  the  capacity  for  breathing  air 
directly.  Some  of  them,  like  the  Frogs  and  Newts,  lose  their 
gills  altogether  on  attaining  the  adult  condition ;  but  others, 
such  as  the  living  Proteus  and  Menobranchus,  retain  their  gills 
even  after  acquiring  their  lungs,  and  are  thus  fitted  indiffer- 
ently for  an  aquatic  or  terrestrial  existence.  The  name  of 
"  Amphibia,"  though  applied  to  the  whole  class,  is  thus  not 
precisely  appropriate  except  to  these  last-mentioned  forms 
(Gr.  ampin,  both ;  bios,  life).  The  Amphibians  also  differ 
amongst  themselves  according  as  to  whether  they  keep  per- 
manently the  long  tail  which  they  all  possess  when  young  (as 
do  the  Newts  and  Salamanders),  or  lose  this  appendage  when 
grown  up  (as  do  the  Frogs  and  Toads).  Most  of  them  have 
naked  skins,  but  a  few  living  and  many  extinct  forms  have 
hard  structures  in  the  shape  of  scales  developed  in  the  integu- 
ment. All  of  them  have  well-ossified  skeletons,  though  some 
fossil  types  are  partially  deficient  in  this  respect ;  and  all  of 
them  which  possess  limbs  at  all  have  these  appendages  sup- 
ported by  bones  essentially  similar  to  those  found  in  the  limbs 
of  the  higher  Vertebrates.  All  the  Carboniferous  Amphibians 
belong  to  a  group  which  has  now  wholly  passed  away — namely, 
that  of  the  Labyrinthodonts.  In  the  marine  strata  which  form 
the  base  of  the  Carboniferous  series  these  creatures  have  only 
been  recognised  by  their  curious  hand- shaped  footprints,  similar 
14 


190 


HISTORICAL  PALAEONTOLOGY. 


in  character  to  those  which  occur  in  theTriassic  rocks,  and  which 
will  be  subsequently  spoken  of  under  the  name  of  Chtirothcrium. 
In  the  Coal-measures  of  Britain,  the  continent  of  Europe,  and 
North  America,  however,  many  bones  of  these  animals  have 
been  found,  and  we  are  now  tolerably  well  acquainted  with  a 
considerable  number  of  forms.  All  of  them  seem  to  have  be- 
longed to  the  division  of  Amphibians  in  which  the  long  tail 
of  the  young  is  permanently  retained ;  and  there  is  evidence 
that  some  of  them  kept  the  gills  also  throughout  life.  The 
skull  is  of  the  characteristic  Amphibian  type  (fig.  132,  a),  with 


Fig.  132.—  a,  Upper  surface  of  the  skull  of  Antkracosaurus  Russelli,  one-sixth  of  the 
natural  size  ;  b,  Part  of  one  of  the  teeth  cut  across,  and  highly  magnified  to  show  the 
characteristic  labyrinthine  structure  ;  c.  One  of  the  integumentary  shields  or  scales,  one- 
half  of  the  natural  size.  Coal-measures,  Northumberland.  (After  Atthey.) 

two  occipital  condyles,  and  having  its  surface  singularly  pitted 
and  sculptured ;  and  the  vertebrae  are  hollowed  out  at  both 
ends.  The  lower  surface  of  the  body  was  defended  by  an 
armour  of  singular  integumentary  shields  or  scales  (fig.  132,  c); 
and  an  extremely  characteristic  feature  (from  which  the  entire 
group  derives  its  name)  is,  that  the  walls  of  the  teeth  are  deeply 
folded,  so  as  to  give  rise  to  an  extraordinary  "  labyrinthine " 
pattern  when  they  are  cut  across  (fig.  132,  b).  Many  of  the 
Carboniferous  Labyrinthodonts  are  of  no  great  size,  some  of 


THE   CARBONIFEROUS    PERIOD.  191 

them  very  small,  but  others  attain  comparatively  gigantic 
dimensions,  though  all  fall  short  in  this  respect  of  the  huge 
examples  of  this  group  which  occur  in  the  Trias.  One  of  the 
largest,  and  at  the  same  time  most  characteristic,  forms  of  the 
Carboniferous  series,  is  the  genus  Anthracosaurus,  the  skull  of 
which  is  here  figured. 

No  remains  of  true  Reptiles,  Birds,  or  Quadrupeds  have  as 
yet  been  certainly  detected  in  the  Carboniferous  deposits  in 
any  part  of  the  world.  It  should,  however,  be  mentioned, 
that  Professor  Marsh,  one  of  the  highest  authorities  on  the 
subject,  has  described  from  the  Coal-formation  of  Nova  Scotia 
certain  vertebrae  which  he  believes  to  have  belonged  to  a 
marine  reptile  (Eosaurus  Acadianus},  allied  to  the  great 
Ichthyosauri  of  the  Lias.  Up  to  this  time  no  confirmation 
of  this  determination  has  been  obtained  by  the  discovery  of 
other  and  more  unquestionable  remains,  and  it  therefore 
remains  doubtful  whether  these  bones  of  Eosaurus  may  not 
really  belong  to  large  Labyrinthodonts. 


LITERATURE' 

The  following  list  contains  some  of  the  more  important  of  the  original 
sources  of  information  to  which  the  student  of  Carboniferous  rocks  and 
fossils  may  I'efer  : — 

(1)  'Geology  of  Yorkshire,'  vol.   ii.  ;  'The  Mountain  Limestone  Dis- 

trict.'    John  Phillips. 

(2)  '  Siluria.'     Sir  Roderick  Murchison. 

(3)  '  Memoirs  of  the  Geological  Survey  of  Great  Britain  and  Ireland.' 

(4)  '  Geological  Report  on  Londonderry,'  &c.     Portlock. 

(5)  '  Acadian  Geology. '     Dawson. 

(6)  'Geology  of  Iowa,'  vol.  i.     James  Hall. 

(7)  *  Reports  of  the  Geological  Survey  of  Illinois '  (Geology  and  Palae- 

ontology).    Meek,  Worthen,  &c. 

(8)  '  Reports  of  the  Geological  Survey  of  Ohio  '  (Geology  and  Palaeon- 

tology).    Newberry,  Cope,  Meek,  Hall,  &c. 

(9)  '  Description  des  Animaux  fossiles  qui  se  trouvent  dans  le  Terrain 

Carbonifere  de  la  Belgique,'  1843  ;  with  subsequent  monographs 
on  the  genera  Productus  and  Chonetes,  on  Crinoids,  on  Ccwals, 
&c.  De  Koninck. 

(10)  '  Synopsis  of  the  Carboniferous  Fossils  of  Ireland.'     M'Coy. 

(n)  '  British  Palaeozoic  Fossils.'     M'Coy. 

(12)  '  Figures  of  Characteristic  British  Fossils.'     Baily. 

(13)  '  Catalogue  of  British  Fossils.'     Morris. 

(14)  '  Monograph  of  the  Carboniferous  Brachiopoda  of  Britain '  (Palseon- 

tographical  Society).      Davidson. 

(15)  '  Monograph  of  the  British  Carboniferous  Corals '  (Palaeontographical 

Society).     Milne-Edwards  and  Haime. 

(16)  '  Monograph  of  the  Carboniferous  Bivalve  Entomostraca  of  Britain' 

(Palaeontographical  Society).  Rupert  Jones,  Kirkby,  and  George 
S.  Brady. 


Ip2  HISTORICAL   PALEONTOLOGY. 

(17)  '  Monograph  of  the  Carboniferous  Foraminifera  of  Britain '  (Palseon- 

tographical  Society).      H.  B.  Brady. 

(18)  "On  the  Carboniferous  Fossils  of  the  West  of  Scotland" — '  Trans. 

Geol.   Soc.,'  of  Glasgow,    vol.  iii.,   Supplement.      Young  and 
Armstrong. 

(19)  'Poissons  Fossiles.'     Agassiz. 

(20)  "Report  on  the  Labyrinthodonts  of  the  Coal-measures"  —  'British 

Association  Report,'  1873.     L.  C.  Miall. 

(21)  'Introduction    to    the    Study   of    Palceontological   Botany.'      John 

Hutton  Balfour. 

(22)  '  Traite  de  Paleontologie  Vegetale.'     Schimper. 

(23)  '  Fossil  Flora.'      Lindley  and  Hutton. 

(24)  '  Histoire  des  Vegetaux  Fossiles.'     Brongniart. 

(25)  *  On  Calamites  and  Calamodendron '  (Monographs  of  the  Palseonto- 

graphical  Society).     Binney. 

(26)  'On   the    Structure   of  Fossil   Plants   found,  in  the  Carboniferous 

Strata'  (Palaeontographical  Society).     Binney. 

Also  numerous  memoirs  by  Huxley,  Davidson,  Martin  Duncan,  Profes- 
sor Young,  John  Young,  R.  Ethericlge,  jun.,  Baily,  Carruthers,  Dawson, 
Binney,  Williamson,  Hooker,  Jukes,  Geikie,  Rupert  Jones,  Salter,  and 
many  other  British  and  foreign  observers. 


CHAPTER     XIV. 
THE    PERMIAN  PERIOD. 

The  Permian  formation  closes  the  long  series  of  the  Palaeo- 
zoic deposits,  and  may  in  some  respects  be  considered  as  a 
kind  of  appendix  to  the  Carboniferous  system,  to  which  it  can- 
not be  compared  in  importance,  either  as  regards  the  actual 
bulk  of  its  sediments  or  the  interest  and  variety  of  its  life- 
record.  Consisting,  as  it  does,  largely  of  red  rocks— sand- 
stones and  marls — for  the  most  part  singularly  destitute  of 
organic  remains,  the  Permian  rocks  have  been  regarded  as  a 
lacustrine  or  fluviatile  deposit;  but  the  presence  of  well-devel- 
•oped  limestones  with  indubitable  marine  remains  entirely 
negatives  this  view.  It  is,  however,  not  improbable  that  we 
are  presented  in  the  Permian  formation,  as  known  to  us  at 
present,  with  a  series  of  sediments  laid  down  in  inland  seas  of 
great  extent,  due  to  £he  subsidence  over  large  areas  of  the 
vast  land-surfaces  of  the  Coal-measures.  This  view,  at  any 
rate,  would  explain  some  of  the  more  puzzling  physical  char- 
acters of  the  formation,  and  would  not  be  definitely  negatived 
by  any  of  its  fossils. 

A  large  portion  of  the  Permian  series,  as  already  remarked, 
consists  of  sandstones  and  marls,  deeply  reddened  by  peroxide 


THE   PERMIAN   PERIOD.  193 

of  iron,  and  often  accompanied  by  beds  of  gypsum  or  deposits 
of  salt.  In  strata  of  this  nature  few  or  no  fossils  are  found; 
but  their  shallow  water  origin  is  sufficiently  proved  by  the 
presence  of  the  footprints  of  terrestrial  animals,  accompanied 
in  some  cases  by  well-defined  "ripple-marks."  Along  with 
these  are  occasionally  found  massive  breccias,  holding  larger 
or  smaller  blocks  derived  from  the  older  formations;  and  these 
have  been  supposed  to  represent  an  old  "  boulder-clay,"  and 
thus  to  indicate  the  prevalence  of  an  arctic  climate.  Beds  of 
this  nature  must  also  have  been  deposited  in  shallow  water. 
In  all  regions,  however,  where  the  Permian  formation  is  well 
developed,  one  of  its  most  characteristic  members  is  a  Mag- 
nesian  limestone,  often  highly  and  fantastically  concretionary, 
but  containing  numerous  remains  of  genuine  marine  animals, 
and  clearly  indicating  that  it  was  deposited  beneath  a  mod- 
erate depth  of  salt  water. 

It  is  not  necessary  to  consider  here  whether  this  formation 
can  be  retained  as  a  distinct  division  of  the  geological  series. 
The  name  of  Permian  was  given  to  it  by  Sir  Roderick  Murchi- 
son,  from  the  province  of  Perm  in  Russia,  where  rocks  of  this 
age  are  extensively  developed.  Formerly  these  rocks  were 
grouped  with  the  succeeding  formation  of  the  Trias  under  the 
common  name  of  "  New  Red  Sandstone."  This  name  was 
given  them  because  they  contain  a  good  deal  of  red  sandstone, 
and  because  they  are  superior  to  the  Carboniferous  rocks, 
while  the  Old  Red  Sandstone  is  inferior.  Nowadays,  how- 
ever, the  term  "  New  Red  Sandstone "  is  rarely  employed, 
unless  it  be  for  red  sandstones  and  associated  rocks,  which 
are  seen  to  overlie  the  Coal  measures,  but  which  contain  no 
fossils  by  which  their  exact  age  may  be  made  out.  Under 
these  circumstances,  it  is  sometimes  convenient  to  employ  the 
term  "  New  Red  Sandstone."  The  New  Red,  however,  of  the 
older  geologists,  is  now  broken  up  into  the  two  formations  of 
the  Permian  and  Triassic  rocks — the  former  being  usually  con- 
sidered as  the  top  of  the  Palaeozoic  series,  and  the  latter  con- 
stituting the  base  of  the  Mesozoic. 

In  many  instances,  the  Permian  rocks  are  seen  to  repose 
unconformably  upon  the  underlying  Carboniferous,  from  which 
they  can  in  addition  be  readily  separated  by  their  lithological 
characters.  In  other  instances,  however,  the  Coal-measures 
terminate  upwards  in  red  rocks,  not  distinguishable  by  their 
mineral  characters  from  the  Permian ;  and  in  other  cases  no 
physical  discordance  between  the  Carboniferous  and  Per- 
mian strata  can  be  detected.  As  a  general  rule,  also,  the 
Permian  rocks  appear  to  pass  upwards  conformably  into  the 


194  HISTORICAL   PALAEONTOLOGY. 

Trias.  The  division,  therefore,  between  the  Permian  and  Tri- 
assic  rocks,  and  consequently  between  the  Palaeozoic  and  Me- 
sozoic  series,  is  not  founded  upon  any  conspicuous  or  universal 
physical  break,  but  upon  the  difference  in  life  which  is  ob- 
served in  comparing  the  marine  animals  of  the  Carboniferous 
and  Permian  with  those  of  the  Trias.  It  is  to  be  observed,  how- 
ever, that  this  difference  can  be  solely  due  to  the  fact  that  the 
Magnesian  Limestone  of  the  Permian  series  presents  us  with 
only  a  small,  and  not  a  typical,  portion  of  the  marine  deposits 
which  must  have  been  accumulated  in  some  area  at  present 
unknown  to  us  during  the  period  which  elapsed  between  the 
formation  of  the  great  marine  limestones  of  the  Lower  Carbon- 
iferous and  the  open-sea  and  likewise  calcareous  sediments  of 
the  Middle  Trias. 

The  Permian  rocks  exhibit  their  most  typical  features  in 
Russia  and  Germany,  though  they  are  very  well  developed  in 
parts  of  Britain,  and  they  occur  in  North  America.  When 
well  developed,  they  exhibit  three  main  divisions  :  a  lower  set 
of  sandstones,  a  middle  group,  generally  calcareous,  and  an 
upper  series  of  sandstones,  constituting  respectively  the  Lower, 
Middle,  and  Upper  Permians. 

In  Russia,  Germany,  and  Britain,  the  Permian  rocks  con- 
sist of  the  following  members  : — 

1.  The  Lower  Permians,  consisting  mainly  of  a  great  series 
of  sandstones,  of  different  colours,  but  usually  red.     The  base 
of  this  series  is  often    constituted   by  massive   breccias  with 
included  fragments  of  the  older  rocks,  upon  which  they  may 
happen  to  repose  ;   and  similar  breccias  sometimes  occur  in 
the  upper  portion  of  the  series  as  well.     The  thickness  of  this 
group  varies  a  good  deal,  but  may  amount  to  3000  or  4000 
feet. 

2.  The   Middle  Permians,   consisting,  in    their   typical  de- 
velopment, of  laminated  marls,  or    "  marl-slate/'  surmounted 
by  beds  of  magnesian  limestone  (the  "Zechstein  "  of  the  Ger- 
man geologists).     Sometimes  the  limestones  are  degenerate  or 
wholly  deficient,  and  the  series  may  consist  of  sandy  shales 
and  gypsiferous  clays.     The  magnesian  limestone,  however,  of 
the  Middle  Permians  is,  as  a  rule,  so  well  marked  a  feature 
that  it  was  long  spoken  of  as  the  Magnesian  Limestone. 

3.  The  Upper  Permians,  consisting  of  a  series  of  sandstones 
and  shales,  or  of  red  or  mottled  marls,  often  gypsiferous,  and 
sometimes  including  beds  of  limestone. 

In  North  America,  the  Permian  rocks  appear  to  be  confined 
to  the  region  west  of  the  Mississippi,  being  especially  well  de- 
veloped in  Kansas.  Their  exact  limits  have  not  as  yet  been 


THE   PERMIAN   PERIOD. 


195 


made  out,  and  their  total  thickness  is  not  more  than  a  few 
hundred  feet.  They  consist  of  sandstones,  conglomerates, 
limestones,  marls,  and  beds  of  gypsum. 

The  following  diagrammatic  section  shows  the  general 
sequence  of  the  Permian  deposits  in  the  north  of  England, 
where  the  series  is  extensively  developed  (fig.  133): — • 


GENERALISED  SECTION  OF  THE  PERMIAN  ROCKS 
IN  THE  NORTH  OF  ENGLAND. 


Fig-  133- 


(  Upper  Red  Sandstones 
\      and  Marls. 


Maenesian  Limestone. 


Marl  Slate. 


Lower  Red  Sandstones 
and  Breccias. 


Coal-measures. 


The  record  of  the  life  of  the  Permian  period  is  but  a  scanty 
one,  owing  doubtless  to  the  special  peculiarities  of  such  of  the 


196  HISTORICAL   PALEONTOLOGY. 

deposits  of  this  age  with  which  we  are  as  yet  acquainted.  Red 
rocks  are,  as  a  general  rule,  more  or  less  completely  unfossil- 
iferous,  and  sediments  of  this  nature  are  highly  characteristic  of 
the  Permian.  Similarly,  magnesian  limestones  are  rarely  as 
highly  charged  with  organic  remains  as  is  the  case  with  normal 
calcareous  deposits,  especially  when  they  have  been  subjected 
to  concretionary  action,  as  is  observable  to  such  a  marked  ex- 
tent in  the  Permian  limestones.  Nevertheless,  much  interest 
is  attached  to  the  organic  remains,  as  marking  a  kind  of  transi- 
tion-period between  the  Palaeozoic  and  Mesozoic  epochs. 

The  plants  of  the  Permian  period,  as  a  whole,  have  a  dis- 
tinctly Palaeozoic  aspect,  and  are  far  more  nearly  allied  to  those 
of  the  Coal-m?asures  than  they  are  to  those  of  the  earlier 
Secondary  rocks ;  though  the  Permian  species  are  mostly  dis- 
tinct from  the  Carboniferous,  and  there  are  some  new  genera. 
Thus,  we  find  species  of  Lepidodendron^  Calamites,  Equisetites, 
Asterophyllites,  Annularia,  and  other  highly  characteristic 
Carboniferous  genera.  On  the  other  hand,  the  Sigillarioids  of 
the  Coal  seem  to  have  finally  disappeared  at  the  close  of  the 
Carboniferous  period.  Ferns  are  abundant  in  the  Permian 
rocks,  and  belong  for  the  most  part  to  the  well  known  Carbon- 
iferous genera  Alethopteris,  Ncuropieris,  Sphenopteris,  and  Pecop- 
teris.  There  are  also  Tree-ferns  referable  to  the  ancient  genus 
Psaronius.  The  Confers  of  the  Permian  period  are  numerous, 
and  belong  in  part  to  Carboniferous  genera.  A  characteristic 
genus,  however,  is  Walchia  (fig.  134),  distinguished  by  its  lax 


Fig.  134.—  Walchia  piniforjttis,  from  the  Permian  of  Saxony. 
a,  Branch ;  b,  Twig.     (After  Gutbier.) 

short  leaves.  This  genus,  though  not  exclusively  Permian,  is 
mainly  so,  the  best -known  species  being  the  W.  piniformis. 
Here,  also,  we  meet  with  Conifers  which  produce  true  cones, 
and  which  differ,  therefore,  in  an  important  degree  from  the 


THE   PERMIAN   PERIOD.  197 

Taxoid  Conifers  of  the  Coal-measures.  Besides  Walchia,  a 
characteristic  form  of  these  is  the  Ullmania  selaginoidcs,  which 
occurs  in  the  Magnesian  Limestone  of  Durham,  the  Middle 
Permian  of  Westmorland,  and  the  "  Kupfer-schiefer "  of  Ger- 
many. The  group  of  the  Cycads,  which  we  shall  subsequently 
find  to  be  so  characteristic  of  the  vegetation  of  the  Secondary 
period,  is,  on  the  other  hand,  only  doubtfully  represented  in 
the  Permian  deposits  by  the  singular  genus  Nceggerathia. 

The  Protozoans  si  the  Permian  rocks  are  few  in  number,  and 
for  the  most  part  imperfectly  known.  A  few  Foraminifcra  have 
been  obtained  from  the  Magnesian  Limestone  of  England, 
and  the  same  formation  has  yielded  some  ill -understood 
Sponges.  It  does  not  seem,  however,  altogether  impossible 
that  some  of  the  singular  "  concretions  "  of  this  formation  may 
ultimately  prove  to  have  an  organic  structure,  though  others 
would  appear  to  be  clearly  of  purely  inorganic  origin.  From 
the  Permian  of  Saxony,  Professor  Geinitz  has  described  two 
species  of  Spongillopsis,  which  he  believes  to  be  most  nearly 
allied  to  the  existing  fresh-water  Sponges  (Sppngilla).  This 
observation  has  an  interest  as  bearing  upon  the  mode  of  de- 
position and  origin  of  the  Permian  sediments. 

The  Ccelenterates  are  represented  in  the  Permian  by  but  a 
few  Corals.  These  belong  partly  to  the  Tabulate,  and  partly 
to  the  Rugose  division  ;  but  the  latter  great  group,  so  abun- 
dantly represented  in  Silurian,  Devonian,  and  Carboniferous 
seas,  is  now  extraordinarily  reduced  in  numbers,  the  British 
strata  of  this  age  yielding  only  species  of  the  single  genus 
Polycoelia.  So  far,  therefore,  as  at  present  known,  all  the 
characteristic  genera  of  the  Rugose  Corals  of  the  Carboniferous 
had  become  extinct  before  the  deposition  of  the  limestones  of 
the  Middle  Permian. 

The  Echinoderms  are  represented  by  a  few  Crinoids,  and  by  a 
Sea-urchin  belonging  to  the  genus  Eoddaris.  The  latter  genus 
is  nearly  allied  to  the  Archceocidaris  of  the  Carboniferous,  so 
that  this  Permian  form  belongs  to  a  characteristically  Palaeozoic 
type. 

A  few  Annelides  (Spirorbis,  Vermilia,  &c.)  have  been  de- 
scribed, but  are  of  no  special  importance.  Amongst  the 
Crustaceans,  however,  we  have  to  note  the  total  absence  of 
the  great  Palaeozoic  group  of  the  Trilobites ;  whilst  the  little 
Ostracoda  and  Phyllopods  still  continue  to  be  represented. 
We  have  also  to  note  the  first  appearance  here  of  the  "  Short- 
tailed  "  Decapods  or  Crabs  (Brachyura),  the  highest  of  all  The 
groups  of  Crustacea,  in  the  person  of  Hcmitrockiscus parado&us, 
an  extremely  minute  Crab  from  the  Permian  of  Germany. 


198  HISTORICAL  PALEONTOLOGY. 

Amongst  the  Mollusca,  the  remains  of  Polyzoa  may  fairly  be 
said  to  be  amongst  the  most  abundant  of  all  the  fossils  of  the 
Permian  formation.  The  principal  forms  of  these  are  the 
fronds  of  the  Lace-corals  (Fenestella,  Retepora,  and  Synocladia}, 
which  are  very  abundant  in  the  Magnesian  Limestone  of  the 
north  of  England,  and  belong  to  various  highly  characteristic 
species  (such  as  Fenestella  retiformis,  Rettpora  Ehrenbergi,  and 
Synocladia  virgulacea).  The  Brachiopoda  are  also  represented 
in  moderate  numbers  in  the  Permian.  Along  with  species  of 
the  persistent  genera  Discing  Crania,  and  Lingula,  we  still 
meet  with  representatives  of  the  old  groups  Spin/era,  Athyris, 
and  Streptorhynchus ;  and  the  Carboniferous  Products  yet 
survive  under  well-marked  and  characteristic  types,  though  in 
much-diminished  numbers.  The  species  of  Brachiopods  here 
figured  (fig.  135)  are  characteristic  of  the  Magnesian  Limestone 
in  Britain  and  of  the  corresponding  strata  on  the  Continent. 


Fig-  135 — Brachiopods  of  the  Permian  formation,    a,  Producta  horricia',  b,    Lingula 
Credtteri;  c,  Terebratula  elongata ;  d  and  e,  CamaropJwria globulina.     (After  King.) 

Upon  the  whole,  the  most  characteristic  Permian  Brachiopods 
belong  to  the  genera  Producta,  Strophalosia,  anci  Camaro- 
phoria. 

The  Bivalves  (Lamellibranchiata)  have  a  tolerably  varied 
development  in  the  Permian  rocks ;  but  nearly  all  the  old 
types,  except  some  of  those  which  occur  in  the  Carboniferous, 
have  now  disappeared.  The  principal  Permian  Bivalves 
belong  to  the  groups  of  the  Pearl  Oysters  (Aviculidcz)  and  the 
Trigoniada,  represented  by  genera  such  as  Bakewellia  and 
Schizodus;  the  true  Mussels  (Mytilid(K\  represented  by  species 
which  have  been  referred  to  Mytilus  itself;  and  the  Arks 
(Arcade),  represented  by  species  of  the  genera  Area  (fig.  136) 
and  Byssoarca.  The  first  and  last  of  these  three  families  have 
a  very  ancient  origin;  but  the  family  of  the  Trigoniadce^  though 


THE   PERMIAN    PERIOD. 


199 


feebly  represented  at  the  present  day,  is  one  which  attained  its 
maximum  development  in  the  Mesozoic  period. 

The  Univalves  (Gasteropoda]  are  rare,  and  do  not  demand 
special  notice.  It  may  be  ob- 
served, however,  that  the  Palseo- 
zoi  J  genera  Euomphalus,  Mur- 
chisonia,  Loxonema,  and  Macro- 
chdlus  are  still  in  existence,  to- 
gether with  the  persistent  genus 
Pleurotomaria.  Pteropods  of  the 
old  genera  T/ieca  and  Comila- 
ria  have  been  discovered ;  but 
the  first  of  these  characteristi- 
cally Palaeozoic  types  finally 
dies  out  here,  and  the  second 
only  survives  but  a  short  time 
longer.  Lastly,  a  few  Cephalopods  have  been  found,  still  wholly 
referable  to  the  Tetrabranchiate  group,  and  belonging  to  the  old 
genera  Orthoceras  and  Cyrtoceras  and  the  long-lived  Nautilus. 

Amongst  Vertebrates,  we  meet  in  the  Permian  period  not 
only  with  the  remains  of  Fishes  and  Amphibians,  but  also,  for 
the  first  time,  with  true  Reptiles.  The  Fishes  are  mainly 
Ganoids,  though  there  are  also  ~emains  of  a  few  Cestraciont 


Fig.  136. — Area  antiqna.     Permian. 


Fig.  137  —  Platysonms  gibbosits,  a  "heterocercal"  Ganoid,  from  the 
Middle  Permian  of  Russia. 

Sharks.  Not  only  are  the  Ganoids  still  the  predominant  group 
of  Fishes,  but  all  the  known  fortns  possess  the  unsymmetrical 
("heterocercal")  tail  which  is  so  characteristic  of  the  Palaeozoic 
Ganoids.  Most  of  the  remains  of  the  Permian  Fishes  have 
been  obtained  from  the  "  Marl-slate "  of  Durham  and  the 
corresponding  "  Kupfer-schiefer  "  of  Germany,  on  the  horizon 


200  HISTORICAL   PALEONTOLOGY. 

of  the  Middle  Permian ;  and  the  principal  genera  of  the 
Ganoids  are  Palceoniscus  and  Platysomus  (fig.  137). 

The  Amphibians  of  the  Permian  period  belong  principally 
to  the  order  of  the  Labyrinihodonts,  which  commenced  to  be 
represented  in  the  Carboniferous,  and  has  a  large  development 
in  the  Trias.  Under  the  name,  however,  of  Palceosiren  Bcinerti, 
Professor  Geinitz  has  described  an  Amphibian  from  the  Lower 
Permian  of  Germany,  which  he  believes  to  be  most  nearly 
allied  to  the  existing  "  Mud-eel "  (Siren  lacertina)  of  North 
America,  and  therefore  to  be  related  to  the  Newts  and  Sala- 
manders (Urodeld], 

Finally,  we  meet  in  the  Permian  deposits  with  the  first  un- 
doubted remains  of  true  Reptiles.  These  are  distinguished,  as 
a  class,  from  the  Amphibians,  by  the  fact  that  they  are  air- 
breathers  throughout  the  whole  of  their  life,  and  therefore  are 
at  no  time  provided  with  gills;  whilst  they  are  exempt  from 
that  metamorphosis  which  all  the  Amphibia  undergo  in  early 
life,  consequent  upon  their  transition  from  an  aquatic  to  a 
more  or  less  purely  aerial  mode  of  respiration.  Their  skel- 
eton is  well  ossified  ;  they  usually  have  horny  or  bony  plates, 
singly  or  in  combination,  developed  in  the  skin;  and  their 
limbs  (when  present)  are  never  either  in  the  form  of  fins  or 
wings,  though  sometimes  capable  of  acting  in  either  of  these 
capacities,  and  liable  to  great  modifications  of  form  and  struc- 
ture. Though  there  can  be  no  doubt  whatever  as  to  the  occur- 
rence of  genuine  Reptiles  in  deposits  of  unquestionable  Per- 
mian age,  there  is  still  uncertainty  as  to  the  precise  number 
of  types  which  may  have  existed  at  this  period.  This  uncer- 
tainty arises  partly  from  the  difficulty  of  deciding  in  all  cases 
whether  a  given  bone  be  truely  Labyrinthodont  or  Reptilian, 
but  more  especially  from  the  confusion  whicji  exists  at  pres- 
ent between  the  Permian  and  the  overlying  Triassic  deposits. 
Thus  there  are  various  deposits  in  different  regions  which 
hate  yielded  the  remains  of  Reptiles,  and  which  cannot  in 
the  meanwhile  be  definitely  referred  either  to  the  Permian 
series  or  to  the  Trias  by  clear  stratigraphical  or  palaeonto- 
logical  evidence.  All  that  can  be  done  in  such  cases  is  to  be 
guided  by  the  characters  of  the  Reptiles  themselves,  and  to 
judge  by  their  affinities  to  remains  from  known  Triassic  or  Per- 
mian rocks  to  which  of  these  formations  the  beds  containing 
them  should  be  referred  ;  but  it  is  obvious  that  this  method 
of  procedure  is  seriously  liable  to  lead  to  error.  In  accor- 
dance, however,  with  this,  the  only  available  mode  of  deter- 
mination in  some  cases,  the  remains  of  Thecodontosaurus  and 
Palaosaurus  discovered  in  the  dolomitic  conglomerates  near 


THE   PERMIAN    PERIOD. 


201 


Bristol  will  be  considered  as  Triassic,  thus  leaving  Protoro- 
saurus  *  as  the  principal  and  most  important  representative  of 


Fig.  *L-$> —Protorosanrits  Speneri,  Middle  Permian,  Thuringia,  reduced  in  size. 
(After  Von  Meyer.)     [Copied  from  Dana.] 

the  Permian  Reptiles.t     The  type-species  of  the  genus  Pro- 
torosaurus  is  the/5.  Speneri  (tig.  138)  of  the  "  Kupfer-schiefer  "  of 

Though  commonly  spelt  as  above,  it  is  probable  that  the  name  of  this 
Lizard  was  really  intended  to  have  been  Preterosaurus—ftom  the  Greek 
proteros,  first ;  and  saura,  lizard  :  and  this  spelling  is  followed  bv  many 
writers. 

t  In  an  extremely  able  paper  upon  the  subject  (Quart.  Journ.  Geol. 
Sex?.,  vol.  xxvi.),  Mr  Etheridge  has  shown  that  there  are  good  physical 
grounds  for  regarding  the  dolomitic  conglomerate  of  Bristol  as  of  Triassic 
age,  and  as  probably  corresponding  in  time  with  the  Muschelkalk  of  the 
Continent. 


202  HISTORICAL   PALEONTOLOGY. 

Thuringia,  but  other  allied  species  have  been  detected  in  the 
Middle  Permian  of  Germany  and  the  north  of  England.  This 
Reptile  attained  a  length  of  from  three  to  four  feet ;  and  it  has 
been  generally  referred  to  the  group  of  the  Lizards  (Lacertilia}, 
to  which  it  is  most  nearly  allied  in  its  general  structure,  at  the 
same  time  that  it  differs  from  all  existing  members  of  this  group 
in  the  fact  that  its  numerous  conical  and  pointed  teeth  were 
implanted  in  distinct  sockets  in  the  jaws — this  being  a  Croco- 
dilian character.  In  other  respects,  however,  Protorosaurus 
approximates  closely  to  the  living  Monitors  ( Vara?iid<z)  •  and 
the  fact  that  the  bodies  of  the  vertebrae  are  slightly  cupped  or 
hollowed  out  at  the  ends  would  lead  to  the  belief  that  the 
animal  was  aquatic  in  its  habits.  At  the  same  time,  the 
structure  of  the  hind-limbs  and  their  bony  supports  proves 
clearly  that  it  must  have  also  possessed  the  power  of  progres- 
sion upon  the  land.  Various  other  Reptilian  bones  have  been 
described  from  the  Permian  formation,  of  which  some  are  pro- 
bably really  referable  to  Labyrinthodonts,  whilst  others  are 
regarded  by  Professor  Owen  as  referable  to  the  order  of  the 
"  Theriodonts,"  in  which  the  teeth  are  implanted  in  sockets, 
and  resemble  those  of  carnivorous  quadrupeds  in  consisting 
of  three  groups  in  each  jaw  (namely,  incisors,  canines,  and 
molars).  Lastly,  in  red  sandstones  of  Permian  age  in  Dum- 
friesshire have  been  discovered  the  tracks  of  what  would  ap- 
pear to  have  been  Chelonians  (Tortoises  and  Turtles);  but  it 
would  not  be  safe  to  accept  this  conclusion  as  certain  upon  the 
evidence  of  footprints  alone.  The  Chelichnus  Duncani,  how- 
ever, described  by  Sir  William  Jardine  in  his  magnificent  work 
on  the  '  Ichnology  of  Annandale/  bears  a  great  resemblance 
to  the  track  of  a  Turtle. 

No  remains  of  Birds  or  Quadrupeds  have  hitherto  been 
detected  in  deposits  of  Permian  age. 


LITERATURE. 

The  following  works  may  be  consulted  by  the  student  with  regard  to  the 
Permian  formation  and  its  fossils  : — 

(1)  "On  the  Geological  Relations  and  Internal  Structure  of  the  Magne- 

sian  Limestone  and  the  Lower  Portions  of  the  New  Red  Sand- 
stone Series,  &c." —  'Trans.  Geol.  Soc.,' ser.  2,  vol.  iii.  Sedg- 
wick. 

(2)  'The  Geology  of  Russia  in  Europe.'     Murchison,  De  Verneuil,  and 

Von  Keyserling. 

(3)  *  Siluria. '     Murchison. 

(4)  *  Permische  System  in  Sachsen.'     Geinitz  and  Gutbier. 

(5)  'Die  Versteinerungen  des  Deutschen  Zechsteingebirges. '     Geinitz. 

(6)  '  Die  Animalischen  Ueberreste  der  Dyas.'     Geinitz. 


THE   TRIASSIC    PERIOD.  203 

(7)  '  Monograph  of  the  Permian  Fossils  of  England'  (Palaeontographical 

Society).     King. 

(8)  'Monograph  of  the  Permian  Brachiopoda  of  Britain'   (Palaeonto- 

graphical  Society).     Davidson. 

(9)  "On  the   Permian  Rocks  of  the  North-West  of  England  and  their 

Extension  into  Scotland" — 'Quart.  Journ.  Geol.  Soc.,'  vol.  xx. 
Murchison  and  Harkness. 

(10)  '  Catalogue  of  the  Fossils  of  the  Permian  System  of  the  Counties  of 

Northumberland  and  Durham.'     Howse. 
(n)  '  Petrefacta  Germanise.'     Goldfuss. 

(12)  '  Beitrage  zur  Petrefaktenkunde. '     Miinster. 

(13)  '  Ein  Beitrag  zur  Palseontologie  des  Deutschen  Zechsteingebirges.' 

Von  Schauroth. 

(14)  '  Saurier  aus  dem  Kupfer-schiefer  der  Zechstein-formation.'     Von 

Meyer. 

(15)  'Manual  of  Palaeontology.'     Owen. 

(16)  '  Recherches  sur  les  Poissons  Fossiles.'     Agassiz. 

(17)  *  Ichnology  of  Annandale.'     Sir  William  Jardine. 

(18)  'Die  Fossile  Flora  der  Permischen  Formation.'     Gceppert. 

(19)  'Genera  et  Species  Plantarum  Fossilium.'     Unger. 

(20)  "  On  the  Red  Rocks  of  England  of  older  Date  than  the  Trias" 

— 'Quart.  Journ.  Geol.  Soc.,'  vol.  xxvii.      Ramsay. 


CHAPTER    XV. 
THE    TRIASSIC  PERIOD. 

We  come  now  to  the  consideration  of  the  great  Mesozoic,  or 
Secondary  series  of  formations,  consisting,  in  ascending  order, 
of  the  Triassic,  Jurassic,  and  Cretaceous  systems.  The  Trias- 
sic  group  forms  the  base  of  the  Mesozoic  series,  and  corre- 
sponds with  the  higher  portion  of  the  New  Red  Sandstone  of 
the  older  geologists.  Like  the  Permian  rocks,  and  as  implied 
by  its  name,  the  Trias*  admits  of  a  subdivision  into  three 
groups — a  Lower,  Middle,  and  Upper  Trias.  Of  these  sub- 
divisions the  middle  one  is  wanting  in  Britain ;  and  all  have 
received  German  names,  being  more  largely  and  typically  de- 
veloped in  Germany  than  in  any  other  country.  Thus,  the 
Lower  Trias  is  known  as  the  Bunter  Sandstein ;  the  Middle 
Trias  is  called  the  Muschelkalk  ;  and  the  Upper  Trias  is  known 
as  the  Keuper. 

I.  The  lowest  division  of  the  Trias  is  known  as  the  Bunter 
Sandstein  (the  Gres  bigarre  of  the  French),  from  the  generally 
variegated  colours  of  the  beds  which  compose  it  (German, 
bunt,  variegated).  The  Bunter  Sandstein  of  the  continent  of 
Europe  consists  of  red  and  white  sandstones,  with  red  clays, 


2O4  HISTORICAL   PALEONTOLOGY. 

and  thin  limestones,  the  whole  attaining  a  thickness  of  about 
1500  feet.  The  term  "marl"  is  very  generally  employed  to 
designate  the  clays  of  the  Lower  and  Upper  Trias ;  but  the 
term  is  inappropriate,  as  they  may  contain  no  lime,  and  are 
therefore  not  always  genuine  marls.  In  Britain  the  Bunter 
Sandstein  consists  of  red  and  mottled  sandstones,  with  uncon- 
solidated  conglomerates,  or  "  pebble-beds,"  the  whole  having 
a  thickness  of  1000  to  2000  feet.  The  Bunter  Sandstein,  as 
a  rule,  is  very  barren  of  fossils. 

II.  The  Middle  Trias  is  not  developed  in  Britain,  but  it 
is  largely  developed  in  Germany,  where  it  constitutes  what  is 
known  as  the  Muschelkalk  (Gevm.  Muschd,  mussel ;  kalk,  lime- 
stone), from  the  abundance  of  fossil  shells  which  it  contains. 
The  Muschelkalk  (the  Calcaire  coqiiillicr  of  the  French)  consists 
of  compact  grey  or  yellowish  limestones,  sometimes  dolomitic, 
and  including  occasional  beds  of  gypsum  and  rock-salt. 

III.  The  Upper  Trias,  or  Kenper  (the  Marnes  irisees  of  the 
French),  as  it  is  generally  called,  occurs  in  England;  but  is 
not  so  well  developed  as  it  is  in  Germany.     In  Britain,  the 
Keuper  is  1000  feet  or  more  in  thickness,  and  consists  of  white 
and  brown  sandstones,  with  red  marls,  the  whole  topped  by 
red  clays  with  rock-salt  and  gypsum. 

The  Keuper  in  Britain  is  extremely  unfossiliferous ;  but  it 
passes  upwards  with  perfect  conformity  into  a  very  remarkable 
group  of  beds,  at  one  time  classed  with  the  Lias,  and  now 
known  under  the  names  of  the  Penarth  beds  (from  Penarth,  in 
Glamorganshire),  the  Rhaetic  beds  (from  the  Rhaetic  Alps),  or 
the  Avicula  contorta  beds  (from  the  occurrence  in  them  of 
great  numbers  of  this  peculiar  Bivalve).  These  singular  beds 
have  been  variously  regarded  as  the  highest  beds  of  the  Trias, 
or  the  lowest  beds  of  the  Lias,  or  as  an  intermediate  group. 
The  phenomena  observed  on  the  Continent,  however,  render 
it  best  to  consider  them  as  Triassic,  as  they  certainly  agree 
with  the  so-called  Upper  St  Cassian  or  Kossen  beds  which 
form  the  top  of  the  Trias  in  the  Austrian  Alps. 

The  Penarth  beds  occur  in  Glamorganshire,  Gloucestershire, 
Warwickshire,  Staffordshire,  and  the  north  of  Ireland;  and 
they  generally  consist  of  a  small  thickness  of  grey  marls,  white 
limestones,  and  black  shales,  surmounted  conformably  by  the 
lowest  beds  of  the  Lias.  The  most  characteristic  fossils  which 
they  contain  are  the  three  Bivalves  Cardium  Rhceticum,  Avictila 
contorta,  and  Pecten  Valoniensis ;  but  they  have  yielded  many 
other  fossils,  amongst  which  the  most  important  are  the  re- 
mains of  Fishes  and  small  Mammals  (Microlestes}. 

In  the  Austrian  Alps  the  Trias  terminates  upwards  in  an 


THE   TRIASSIC    PERIOD. 


205 


extraordinary  series  of  fossiliferous  beds,  replete  with  marine 
fossils.  Sir  Charles  Lyell  gives  the  following  table  of  these 
remarkable  deposits  :— 


Strata  belcnv  the  Lias  in  the  Austrian  Alps,  in  descending  order. 


i.   Koessen  beds. 

(Synonyms,  Upper  St 
Cassian  beds  of  Escher\ 
and  Merian.)  , 


2.  Dachstein  beds. 


3.  Hallstadt  beds 

(or  St  Cassian). 


4.   A.  Guttenstein  beds. 
B.  Werfen  beds,  base  of 

Upper  Trias  ? 
Lower  Trias  of  some 
geologists. 


Grey  and  black  limestone,  with  calcareous 
marls  having  a  thickness  of  about  50 
feet.  Among  the  fossils,  Brachiopoda 
very  numerous  ;  some  few  species  com- 
mon to  the  genuine  Lias  ;  many  pecu- 
liar. AvicTila  contorta,  Pecten  Valo- 
niensis,  Cardium  Rhceticum,  Avicula 
inczqnivalvis,  Spirifer  Miinsteri,  Dav. 
Strata  containing  the  above  fossils  al- 
ternate with  the  Dachstein  beds,  lying 
next  below. 

White  or  greyish  limestone,  often  in  beds 
three  or  four  feet  thick.  Total  thick- 
ness of  the  formation  above  2000  feet. 
Upper  part  fossiliferous,  with  some 
strata  composed  of  corals  (Lithoden- 
dron.)  Lower  portion  without  fossils. 
Among  the  characteristic  shells  are  He- 
micardium  Wulfeni,  Megalodon  triqueter, 
and  other  large  bivalves. 

Red,  pink,  or  white  marbles,  from  800  to 
1000  feet  in  thickness,  containing  more 
than  800  species  of  marine  fossils,  for 
the  most  part,  mollusca.  Many  species 
of  Orthoceras.  True  Ammonites,  besides 
Ceratites  and  Goniatites,  Belemnites  (rare), 
Porcellia,  Pleurotomaria,  Trochns,  Mono- 
tis  salinaria,  &c. 

A.  Black  and  grey  lime- 
stone 150  feet  thick,  al- 
ternating with  the  un- 
derlying Werfen  beds. 

B.  Red  and  green  shale 
and     sandstone,     with 
salt  and  gypsum. 


Among  the  fossils 
are  Ceratites 
cassianns,  My- 
acites  fassaen- 
sis,  Nat  ice  La 
costata,  &c. 


In  the  United  States,  rocks  of  Triassic  age  occur  in  several 
areas  between  the  Appalachians  and  the  Atlantic  seaboard ; 
but  they  show  no  such  triple  division  as  in  Germany,  and  their 
exact  place  in  the  system  is  uncertain.  The  rocks  of  these 
areas  consist  of  red  sandstones,  sometimes  shaly  or  conglomer- 
atic, occasionally  with  beds  of  impure  limestone.  Other  more 
extensive  areas  where  Triassic  rocks  appear  at  the  surface,  are 
found  west  of  the  Mississippi,  on  the  slopes  of  the  Rocky  Moun- 
tains, where  the  beds  consist  of  sandstones  and  gypsiferous 
15 


206 


HISTORICAL   PALEONTOLOGY. 


marls.  The  American  Trias  is  chiefly  remarkable  for  having 
yielded  the  remains  of  a  small  Marsupial  (Dromatherium),  and 
numerous  footprints,  which  have  generally  been  referred  to 
Birds  (Brontozouni),  along  with  the  tracks  of  undoubted  Rep- 
tiles (Otozoum,  Anisopus,  &c.) 

The  subjoined  section  (fig.  139)  expresses,  in  a  diagram- 
matic manner,  the  general  sequence  of  the  Triassic  rocks  when 
fully  developed,  as,  for  example,  in  the  Bavarian  Alps : — 

GENERALISED  SECTION  OF  THE  TRIASSIC  ROCKS  OF 
CENTRAL  EUROPE. 


w    . 

*< 

Q 


Fig.  139- 


v. 


I  Upper   Keuper   (Kossen   or 

[> j      Rhaetic  beds,  and   Dach- 

f       stein  beds). 


1    I    I 


V>lVVll  VVVV 


»   II  . «  H   »  »    II . » .. " 

'    "      "     »    II .,  II     H     " 


I'  .   "     I'    ".  »     " 


JUl 


0000 


(/        o      O      w      -O 


Middle    Keuper    (Hallstadt 
or  St  Cassian  beds). 


(  Lower      Keuper      (Keuper 
Sandstones  proper). 


Muschelkalk. 


Bunter  Sandstein.   (Gutten- 
stein  and  Werfen  beds?) 


With  .regard  to  the  life  of  the  Triassic  period,  we  have  to 


THE   TRIASSIC    PERIOD.  2O/ 

notice  a  difference  as  concerns  the  different  members  of  the 
group  similar  to  that  which  has  been  already  mentioned  in 
connection  with  the  Permian  formation.  The  arenaceous 
deposits  of  the  series,  namely,  resemble  those  of  the  Permian, 
not  only  in  being  commonly  red  or  variegated  in  their  colour, 
but  also  in  their  conspicuous  paucity  of  organic  remains. 
They  for  the  most  part  are  either  wholly  unfossiliferous,  or 
they  contain  the  remains  of  plants  or  the  bones  of  reptiles, 
such  as  may  easily  have  been  drifted  from  some  neighbouring 
shore.  The  few  fossils  which  may  be  considered  as  properly 
belonging  to  these  deposits  are  chiefly  Crustaceans  (Estheria) 
or  Fishes,  which  may  well  have  lived  in  the  waters  of  estuaries 
or  vast  inland  seas.  We  may  therefore  conclude,  with  con- 
siderable probability,  that  the  barren  sandy  and  marly  accumu- 
lations of  the  Burner  Sandstein  and  Lower  Keuper  \vere  not 
laid  down  in  an  open  sea,  but  are  probably  brackish-water 
deposits,  formed  in  estuaries  or  land-locked  bodies  of  salt 
water.  This  at  any  rate  would  appear  to  be  the  case  as  regards 
these  members  of  the  series  as  developed  in  Britain  and  in 
their  typical  areas  on  the  continent  of  Europe  ;  and  the  origin 
of  most  of  the  North  American  Trias  would  appear  to  be 
much  the  same.  Whether  this  view  be  correct  or  not,  it  is 
certain  that  the  beds  in  question  were  laid  down  in  shallow 
water,  and  in  the  immediate  vicinity  of  land,  as  shown  by  the 
numerous  drifted  plants  which  they  contain  and  the  common 
occurrence  in  them  of  the  footprints  of  air-breathing  animals 
(Birds,  Reptiles,  and  Amphibians).  On  the  other  hand,  the 
middle  and  highest  members  of  the  Trias  are  largely  calca- 
reous, and  are  replete  with  the  remains  of  undoubted  marine 
animals.  There  cannot,  therefore,  be  the  smallest  doubt  but 
that  the  Muschelkalk  and  the  Rhaetic  or  Kossen  beds  were 
slowly  accumulated  in  an  open  sea,  of  at  least  a  moderate 
depth  ;  and  they  have  preserved  for  us  a  very  considerable 
selection  from  the  marine  fauna  of  the  Triassic  period. 

The  plants  of  the  Trias  are,  on  the  whole,  as  distinctively 
Mesozoic  in  their  aspect  as  those  of  the  Permian  are  Palaeo- 
zoic. In  spite,  therefore,  of  the  great  difficulty  which  is  ex- 
perienced in  effecting  a  satisfactory  strati  graphical  separation 
between  the  Permian  and  the  Trias,  we  have  in  this  fact  a 
proof  that  the  two  formations  were  divided  by  an  interval  of 
time  sufficient  to  allow  of  enormous  changes  in  the  terrestrial 
vegetation  of  the  world.  The  Lepidodendroids,  Asterophyllites, 
and  Annularies,  of  the  Coal  and  Permian  formations,  have  now 
apparently  wholly  disappeared  ;  and  the  Triassic  flora  consists 
mainly  of  Ferns,  Cycads,  and  Conifers,  of  which  only  the  two 


2O8  HISTORICAL   PALEONTOLOGY. 

last  need  special  notice.     The  Cycads  (fig.  140)  are  true  exo- 
genous plants,  which  in  general  form  and  habit  of  growth  pre- 


Fig.  140. — Zamia  spirals,  a  living  Cycad.     Australia. 

sent  considerable  resemblance  to  young  Palms,  but  which  in 
reality  are  most  nearly  related  to  the  Pines  and  Firs  (Coniftrai). 
The  trunk  is  unbranched,  often  much  shortened,  and  bears  a 
crown  of  feathery  pinnate  fronds.  The  leaves  are  usually 
"  circinate "  •  —  they  unroll  in  expanding,  like  the  fronds  of 
ferns.  The  seeds  are  not  protected  by  a  seed-vessel,  but  are 
borne  upon  the  edge  of  altered  leaves,  or  are  carried  on  the 
scales  of  a  cone.  All  the  living  species  of  Cycads  are  natives 
of  warm  countries,  such  as  South  America,  the  West  Indies, 
Japan,  Australia,  Southern  Ask,  and  South  Africa.  The 
remains  of  Cycads,  as  we  have  seen,  are  not  known  to  occur 
in  the  Coal  formation,  or  only  to  a  very  limited  extent  towards 
its  close;  nor  are  they  known  with  certainty  as  occurring  in 
Permian  deposits.  In  the  Triassic  period,  however,  the  re- 
mains of  Cycads  belonging  to  such  genera  as  Pterophyllum 
(fig.  141,  $),  Zamites,  and  Podozamites  (fig.  141,  c\  are  suffi- 
ciently abundant  to  constitute  quite  a  marked  feature  in  the 
vegetation ;  and  they  continue  to  be  abundantly  represented 
throughout  the  whole  Mesozoic  series.  The  name  "  Age  of 
Cycads,"  as  applied  to  the  Secondary  epoch,  is  therefore, 
from  a  botanical  point  of  view,  an  extremely  appropriate  one. 
The  Conifers  of  the  Trias  are  not  uncommon,  the  principal 
form  being  Voltzia  (fig.  141,  a\  which  possesses  some  peculiar 
characters,  but  would  appear  to  be  most  nearly  related  to  the 
recent  Cypresses. 

As  regards  the  Invertebrate  animals  of  the  Trias,  our  know- 
ledge is  still  principally  derived  from  the  calcareous  beds 
which  constitute  the  centre  of  the  system  (the  Muschelkalk) 


THE   TRIASSIC   PERIOD.  209 

on  the  continent  of  Europe,  and  from   the  St  Cassian  and 
Rhaetic  beds  still  higher  in  the  series;   whilst  some  of  the 


Fig.  141. — Triassic  Conifers  and. Cycads.  a,  Voltzia  (Schizoneura)  heterophyllat-pa<c- 
tion  of  a  branch,  Europe  and  America ;  b,  Part  of  the  frond  of  Pteropkyllutn  Jcegeri, 
Europe;  c,  Part  of  the  frond  of  Podozamites  lanceolatus,  America. 

Triassic  strata  of  California  and  Nevada  have  likewise  yielded 
numerous  remains  of  marine  Invertebrates.  The  Protozoans 
are  represented  by  Foraminifera  and  Sponges,  and  the  Ccelen- 
terates  by  a  small  number  of  Corals ;  but  these  require  no 
special  notice.  It  may  be  mentioned,  however,  that  the  great 
Palaeozoic  group  of  the  Riigose  corals  has  no  known  repre- 
sentative here,  its  place  being  taken  by  corals  of  Secondary 
type  (such  as  Montlivaltia,  Synastrcza,  &c.) 

The  Echinoderms  are  represented  principally  by  Crinoids, 
the  remains  of  which  are  extremely  abundant  in  some  of  the 
limestones.  The  best-known  species  is  the  famous  "  Lily- 
Encrinite  "  (Encritms  liliiformis,  fig.  142),  which  is  character- 


210 


HISTORICAL    PALAEONTOLOGY. 


istic  of  the  Muschelkalk.  In  this  beautiful  species,  the  flower- 
like  head  is  supported  upon  a  rounded  stem,  the  joints  of 
which  are  elaborately  articulated  with  one 
another ;  and  the  fringed  arms  are  com- 
posed each  of  a  double  series  of  alter- 
nating calcareous  pieces.  The  Palaeozoic 
Urchins,  with  their  supernumerary  rows  of 
plates,  the  Cystideans,  and  the  Pentremites 
have  finally  disappeared ;  but  both  Star- 
fishes and  Brittle-stars  continue  to  be  rep- 
resented. One  of  the  latter — namely,  the 
Aspidura  loricata  of  Goldfuss  (tig.  143) — is 


Fig.  143. — As/>idnra  loricata,  a  Triassic  Ophiuroid. 
Muschelkalk,  Germany. 

highly  characteristic  of  the  Muschelkalk. 

The  remains  of  Articulate  Animals  are 
not  very  abundant  in  the  Trias,  if  we  except 
the  bivalved  cases  of  the  little  Water-fleas 
(Ostracoda],  which  are  occasionally  very 
plentiful.  There  are  also  many  species 
of  the  horny,  concentrically-striated  valves 
of  the  Estheria  (see  fig.  122,  b\  which 
might  easily  be  taken  for  small  Bivalve 
Molluscs.  The  "Long-tailed"  Decapods, 
of  the  type  of  the  Lobster,  are  not  with- 
out examples,  but  they  become  much  more 
numerous  in  the  succeeding  Jurassic  pe- 
riod. Remains  of  insects  have  also  been  discovered. 

Amongst  the  Mollusca  we  have  to  note  the  disappearance, 
amongst  the  lower  groups,  of  many  characteristic  Palaeozoic 
types.  Amongst  the  Poly  wans,  the  characteristic  "  Lace- 
corals,"  Fenestella,  Retepora*  Synocladia,  Polypora,  &c.,  have 

*  The  genus  Retepora  is  really  a  recent  one,  represented  by  living  forms  ; 
and  the  so-called  -Reteporce  of  the  Palaeozoic  rocks  should  properly  receive 
another  name  (Phyllopora\  as  being  of  ?..  different  nature.  The  name 
Retepora  has  been  here  retained  for  these  old  forms  simply  in  accordance 
with  genera!  usage. 


Fig.  142. — Head  and 
upper  part  of  the  column 
of  Encrintts  liliiformis. 
The  lower  figure  shows 
the  articulating  surface 
of  one  of  the  joints  of  the 
column.  Muschelkalk, 
Germany. 


THE  TRIASSIC   PERIOD. 


211 


become  apparently  extinct.  The  same  is  true  of  many  of  the 
ancient  types  of  Brachiopods,  and  conspicuously  so  of  the 
great  family  of  the  Productida,  which  played  such  an  important 
part  in  the  seas  of  the  Carboniferous  and  Permian  periods. 

Bivalves  (Lamellibranchiatd)  and  Univalves  (Gasteropoda) 
are  well  represented  in  the  marine  beds  of  the  Trias,  and 
some  of  the  former  are  particularly  characteristic  either  of  the 
formation  as  a  whole  or  of  minor  subdivisions  of  it.  A  few  of 
these  characteristic  species  are  figured  in  the  accompanying 
illustration  (fig.  144).  Bivalve  shells  of  the  genera  Daonella 
(fig.  144,  a)  and  Halobia  (Monotis]  are  very  abundant,  and  are 


Fig.   144.     Triassic  Lamellibranchs.     a,   Daonella  (Halobia)   LommelU  ;    b,    Pecten 
Valoniensis;   c,  Myophoria  lineata;   d,  Cardium  Rhceticum;    e,  Avlcula  contorta; 
jf,  A  vicula  socialis. 

found  in  the  Triassic  strata  of  almost  all  regions.  These 
groups  belong  to  the  family  of  the  Pearl-oysters  (Aviculida), 
and  are  singular  from  the  striking  resemblance  borne  by  some 
of  their  included  forms  to  the  Strophomena  amongst  the  Lamp- 
shells,  though,  of  course,  no  real  relation  exists  between  the 
two.  The  little  Pearl-oyster,  Aviada  socialis  (fig.  144,  /),  is 
found  throughout  the  greater  part  of  the  Triassic  series,  and  is 
especially  abundant  in  the  Muschelkalk.  The  genus  Myo- 
phoria (fig.  144,  c\  belonging  to  the  Trigoniada,  and  related 
therefore  to  the  Permian  Schizodus,  is  characteristically  Trias- 
sic, many  species  of  the  germs  being  known  in  deposits  of  this 
?.ge.  Lastly,  the  so-called  "  Rhsetic"  or  "  Kossen"  beds  are 


212 


HISTORICAL   PALEONTOLOGY. 


characterised  by  the  occurrence  in  them  of  the  Scallop,  Pecten 
Valoniensis  (fig.  144,  b];  the  small  Cockle,  Cardium  Rh&ticum 
(fig.  144,  d)j  and  the  curiously-twisted  Pearl-oyster,  Avicula 
contorta  (fig.  144,  e] — this  last  Bivalve  being  so  abundant  that 
the  strata  in  question  are  often  spoken  of  as  the  "  Avicula 
contorta  beds." 

Passing  over  the  groups  of  the  Heteropods  and  Pteropods, 
we  have  to  notice  the  Cephalopoda,  which  are  represented  in 
the  Trias  not  only  by  the  chambered  shells  of  Tetrabranchiates, 
but  also,  for  the  first  time,  by  the  internal  skeletons  of  Dibran- 
chiate  forms.  The  Trias,  therefore,  marks  the  first  recognised 
appearance  of  true  Cuttle-fishes.  All  the  known  examples  of 
these  belong  to  the  great  Mesozoic  group  of  the  Belemnitidce ; 
and  as  this  family  is  much  more  largely  developed  in  the  suc- 
ceeding Jurassic  period,  the  consideration  of  its  characters 
will  be  deferred  till  that  formation  is  treated  of.  Amongst  the 
chambered  Cephalopods  we  find  quite  a  number  of  the  Palae- 
ozoic Orthoceratites,  some  of  them  of  considerable  size,  along 
with  the  ancient  Cyitoceras  and  Goniatites  ;  and  these  old  types, 
singularly  enough,  occur  in  the  higher  portion  of  the  Trias 
(St  Cassian  beds),  but  have,  for  some  unexplained  reason,  not 
yet  been  recognised  in  the  lower  and  equally  fossiliferous 
formation  of  the  Muschelkalk.  Along  with  these  we  meet  for 
the  first  time  with  true  Ammonites,  which  fill  such  an  extensive 

place  in  the  Jurassic 
seas,  and  which  will 
be  spoken  of  nere. 

after.  The  form,  how- 
ever, which  is  most 
characteristic  of  the 
Trias  is  Ceratites  (fig. 
145).  In  this  genus 
the  shell  is  curved  into 
a  flat  spiral,  the  volu- 
tions of  which  are  in 
contact ;  and  it  further 
agrees  with  both  Go- 
ff/Vz/A&rand  Ammonites 
in  the  fact  that  the 
septa  or  partitions  be- 
tween the  air-cham- 
bers are  not  simple  and  plain  (as  in  the  Nautilus  and  its  allies), 
but  are  folded  and  bent  as  they  approach  the  outer  wall  of  the 
shell.  In  the  Goniatite  these  foldings  of  the  septa  are  of  a  simply 
lobed  or  angulated  nature,  and  in  the  Ammonite  they  are  ex- 


Fig-.  145. — Ceratites  nodosus,  viewed  from  the  side 
and  from  behind.     Muschelkalk. 


THE   TRIASSIC    PERIOD. 


213 


tremely  complex;  whilst  in  the  Ceratite  there  is  an  inter- 
mediate state  of  things,  the  special  feature  of  which  is,  that 
those  foldings  which  are  turned  towards  the  mouth  of  the 
shell  are  merely  rounded,  whereas  those  which  are  turned 
away  from  the  mouth  are  characteristically  toothed.  The 
genus  Ceratites,  though  principally  Triassic,  has  recently  been 
recognised  in  strata  of  Carboniferous  age  in  India. 

From  the  foregoing  it  will  be  gathered  that  one  of  the  most 
important  points  in  connection  with  the  Triassic  Mollusca  is 
the  remarkable  intermixture  of  Palaeozoic  and  Mesozoic  types 
which  they  exhibit.  It  is  to  be  remembered,  also,  that  this 
intermixture  has  hitherto  been  recognised,  not  in  the  Middle 
Triassic  limestones  of  the  Muschelkalk,  in  which — as  the 
oldest  Triassic  beds  with  marine  fossils — we  should  naturally 
expect  to  find  it,  but  in  the  St  Cassian  beds,  the  age  of  which 
is  considerably  later  than  that  of  the  Muschelkalk.  The 
intermingling  of  old  and  new  types  of  Shell-fish  in  the  Upper 
Trias  is  well  brought  out  in  the  annexed  table,  given  by  Sir 
Charles  Lyell  in  his  'Student's  Elements  of  Geology'  (some 
of  the  less  important  forms  in  the  table  being  omitted  here): — 

GENERA  OF  FOSSIL  MOLLUSCA  IN  THE  ST  CASSIAN 
AND  HALLSTADT  BEDS. 


Common  to  Older  Rocks. 

Characteristic  of  Triassic 
Rocks. 

Common  to  Newer  Rocks. 

Orthoceras. 

Ceratites. 

Ammonites. 

Bactrites. 

Cochloceras. 

Chemnitzia. 

Macrocheilus. 

Rhabdoceras. 

Cerithium. 

Loxonema. 

Aulacoceras. 

Monodonta. 

Holopella. 

Naticella. 

Sphcera. 

Murchisonia. 

Platystoma. 

Cardita. 

Porcellia. 

Halobia. 

Myoconcha. 

Athyris. 

Hornesia. 

Hinnites. 

Retzia. 

Kontnckia. 

Monotis. 

Cyrtina. 

Scoliostoma. 

Plicatula. 

Euomphalus. 

Myophoria. 

Pachyrisma. 

(The  last  two  are  princi- 

Thecidium. 

pally  but   not  exclus- 

ively Triassic.  ) 

Thus,  to  emphasise  the  more  important  points  alone,  the  Trias 
has  yielded,  amongst  the  Gasteropods,  the  characteristically 
Palaeozoic  Loxonema,  Holopella,  Murchisonia,  Euomphalus,  and 
Porcellia,  along  with  typically  Triassic.  forms  like  Platystoma 
and  Scoliostoma,  and  the  great  modern  groups  Chemnitzia  and 
Cerithium.  Amongst  the  Bivalves  we  find  the  Palaeozoic 
Megalodon  side  by  side  with  the  Triassic  Jjalobia  and  Myo- 
phoria, these  being  associated  with  the  Carditcz,  Hinnites, 
Plicatulce,  and  Trigonics  of  later  deposits.  The  Brachiopods 


214  HISTORICAL   PALAEONTOLOGY. 

exhibit  the  Palaeozoic  Athyris,  Retzia,  and  Cyrtina,  with  the 
Triassic  Koninckia  and  the  modern  Thecidium.  Finally,  it  is 
here  that  the  ancient  genera  Orthoceras,  Cyrtoceras,  and  Gonia- 
tites  make  their  last  appearance  upon  the  scene  of  life,  the 
place  of  the  last  of  these  being  taken  by  the  more  complex 
and  almost  exclusively  Triassic  Ceratites  ;  whilst  the  still  more 
complex  genus  Ammonites  first  appears  here  in  force,  and  is 
never  again  wanting  till  we  reach  the  close  of  the  Mesozoic 
period.  The  first  representatives  of  the  great  Secondary 
family  of  the  Belemnites  are  also  recorded  from  this  horizon. 

Amongst  the  Vertebrate  Animals  of  the  Trias,  the  Fishes  are 
represented  by  numerous  forms  belonging  to  the  Ganoids  and 
the  Placoids.  The  Ganoids  of  the  period  are  still  all  provided 
with  unsymmetrical  ("heterocercal")  tails,  and  belong  prin- 
cipally to  such  genera  as  Palceoniscus  and  Catopterus.  The 
remains  of  Placoids  are  in  the  form  of  teeth  and  spines,  the 
two  principal  genera  being  the  two  important  Secondary 
groups  Acrodus  and  Hybodus.  Very  nearly  at  the  summit 
of  the  Trias  in  England,  in  the  Rhaetic  series,  is  a  singular 
stratum,  which  is  well  known  as  the  "  bone-bed,"  from  the 
number  of  fish-remains  which  it  contains.  More  interesting, 
however,  than  the  above,  are  the  curious  palate-teeth  of  the 
Trias,  upon  which  Agassiz  founded  the  genus  Ceratodus.  The 
teeth  of  Ceratodus  (fig.  146)  are  singular  flattened  plates, 


Fig.  146.—  a,  Dental  plate  of  Ceratodus  serratus,  Keuper;  b,  Dental  plate  of 
Ceratodus  altus,  Keuper.     (After  Agassiz.) 

composed  of  spongy  bone  beneath,  covered  superficially  with 
a  layer  of  enamel.  Each  plate  is  approximately  triangular, 
one  margin  (which  we  now  know  to  be  the  outer  one)  being 
prolonged  into  prongs  or  conical  prominences,  whilst  the 
surface  is  more  or  less  regularly  undulated.  Until  recently, 
though  the  master-mind  of  Agassiz  recognised  that  these 
singular  bodies  were  undoubtedly  the  teeth  of  fishes,  we  were 
entirely  ignorant  as  to  their  precise  relation  to  the  animal,  or 
as  to  the  exact  affinities  of  the  fish  thus  armed.  Lately,  how- 
ever, there  has  been  discovered  in  the  rivers  of  Queensland 
.(Australia)  a  living  species  of  Ceratodus  (C.  Fosieri,  fig.  147), 


THE   TRIASSIC   PERIOD.  21$ 

with  teeth  precisely  similar  to  those  of  its  Triassic  predecessor ; 
and  we  thus  have  become  acquainted  with  the  use  of  these 


Fig.  147. — Ceratodus  Fosteri,  the  Australian  Mud-fish,  reduced  in  size. 

structures  and  the  manner  in  which  they  were  implanted  in 
the  mouth.  The  palate  carries  two  of  these  plates,  with  their 
longer  straight  sides  turned  towards  each  other,  their  sharply- 
sinuated  sides  turned  outwards,  and  their  short  straight  sides 
or  bases  directed  backwards.  Two  similar  plates  in  the  lower 
jaw  correspond  to  the  upper,  their  undulated  surfaces  fitting 
exactly  to  those  of  the  opposite  teeth.  There  are  also  two 
sharp-edged  front  teeth,  which  are  placed  in  the  front  of  the 
mouth  in  the  upper  jaw;  but  these  have  not  been  recognised 
in  the  fossil  specimens.  The  living  Ceratodus  feeds  on  vege- 
table matters,  which  are  taken  up  or  torn  off  from  plants  by 
the  sharp  front  teeth,  and  then  partially  crushed  between  the 
undulated  surfaces  of  the  back  teeth  (Giinther) ;  and  there 
need  be  little  doubt  but  that  the  Triassic  Ceratodi  followed 
a  similar  mode  of  existence.  From  the  study  of  the  living 
Ceratodus,  it  is  certain  that  the  genus  belongs  to  the  same 
group  as  the  existing  Mud-fishes  {Dipnoi};  and  we  therefore 
learn  that  this,  the  highest,  group  of  the  entire  class  of  Fishes 
existed  in  Triassic  times  under  forms  little  or  not  at  all  differ- 
ent from  species  now  alive ;  whilst  it  has  become  probable 
that  the  order  can  be  traced  back  into  the  Devonian  period. 

The  Amphibians  of  the  Trias  all  belong  to  the  old  order  of 
the  Labyrinthodonts,  and  some  of  them  are  remarkable  for 
their  gigantic  dimensions.  They  were  first  known  by  their 
footprints,  which  were  found  to  occur  plentifully  in  the  Tri- 
assic sandstones  of  Britain  and  the  continent  of  Europe,  and 
which  consisted  of  a  double  series  of  alternately-placed  pairs 
of  hand-shaped  impressions,  the  hinder  print  of  each  pair  being 
much  larger  than  the  one  in  front  (fig.  148).  So  like  were  these 
impressions  to  the  shape  of  the  human  hand,  that  the  at  that 
time  unknown  animal  which  produced  them  was  at  once  chris- 
tened Cheirotherium,  or  "  Hand-beast."  Further  discoveries, 
however,  soon  showed  that  the  footprints  of  Cheirotherium 
were  really  produced  by  species  of  Amphibians  which,  like  the 
existing  Frogs,  possessed  hind-feet  of  a  much  larger  size  than 


216 


HISTORICAL   PALEONTOLOGY. 


the  fore-feet,  and  to  which  the 
name  of  Labyrinthodonts  was  ap- 
plied in  consequence  of  the 
complex  microscopic  structure  of 
the  teeth  (fig.  149).  In  the  essen- 
tial details  of  their  structure,  the 
Triassic  Labyrinthodonts  did  not 
differ  materially  from  their  pre- 
decessors in  the  Coal-measures 
and  Permian  rocks.  They  pos- 
sessed the  same  frog-like  skuils 
(fig.  150),  with  a  lizard-like  body, 
a  long  tail,  and  comparatively 
feeble  limbs.  The  hind -limbs 
were  stronger  and  longer  than 
the  fore -limbs,  and  the  lower 


Fig.  148. — Footprints  of  a  Labyrinthodont  (Cheirotkeriunf),  from  the  Triassic  Sand- 
stones of  Hessberg,  near  Hildburghausen,  Germany,  reduced  one-eighth.  The  lower 
figure  shows  a  slab,  with  several  prints,  and  traversed  by  reticulated  sun-cracks  :  the 
upper  figure  shows  the  impression  uf  one  of  the  hind-feet,  one-half  of  the  natural  size. 
(.-\fter  Sickler.) 


THE   TRIASSIC    PERIOD. 

surface  of  the  body  was  protected  by  an  armour  of  bony  plates. 
Some  of  the  Triassic  Labyrinthodonts  must  have  attained 
dimensions  utterly  unapproached  amongst  existing  Amphibians, 
the  skull  of  Labyrinthodon  Jageri  (fig.  150)  being  upwards  of 


Fig.  149.— Section  of  the  tooth  of  Labyrinthodon 
Mastodonsaurus)  Ja-geri,  showing  the  microscopic 
structure.  Greatly  enlarged.  Trias. 


Fig.  150.— a,  Skull  of  La- 
lyrinthodon  j&geri,  much 
reduced  in  size  ;  b,  Tooth 
of  the  same.  Trias,  Wiirt- 
temberg. 


three  feet  in  length  and  two  feet  in  breadth.  Restorations  of 
some  of  these  extraordinary  creatures  have  been  attempted  in 
the  guise  of  colossal  Frogs ;  but  they  must  in  reality  have  more 
closely  resembled  huge  Newts. 

Remains  of  Reptiles  are  very  abundant  in  Triassic  deposits, 
and  belong  to  very  varied  types.  The  most  marked  feature, 
in  fact,  connected  with  the  Vertebrate  fauna  of  the  Trias,  and 
of  the  Secondary  rocks  in  general,  is  the  great  abundance  of 
Reptilian  life.  Hence  the  Secondary  period  is  often  spoken 
of  as  the  ."  Age  of  Reptiles."  Many  of  the  Triassic  reptiles 
depart  widely  in  their  structure  from  any  with  which  we  are 
acquainted  as  existing  on  the  earth  at  the  present  day,  and  it  is 
only  possible  here  to  briefly  note  some  of  the  more  important 
of  these  ancient  forms.  Amongst  the  group  of  the  Lizards 
(Lacertiha\  represented  by  Protorosaurus  in  the  older  Permian 
strata,  three  types  more  or  less  certainly  referable  to  this  order 
may  be  mentioned.  One  of  these  is  a  small  reptile  which 
was  found  many  years  ago  in  sandstones  near  Elgin,  in  Scot- 
land, and  which  excited  special  interest  at  the  time  in  conse- 
quence of  the  fact  that  the  strata  in  question  were  believed  to 
belong  to  the  Old  Red  Sandstone  formation.  It  is,  however, 


2l8  HISTORICAL   PALEONTOLOGY. 

now  certain  that  the  Elgin  sandstones  which  contain  Telerpeton 
Elginense,  as  this  reptile  is  termed,  are  really  to  be  regarded  as 
of  Triassic  age.  By  Professor  Huxley,  Telerpeton  is  regarded 
as  a  Lizard,  which  cannot  be  considered  as  "  in  any  sense 
a  less  perfectly  -  organised  creature  than  the  Gecko,  whose 
swift  and  noiseless  run  over  walls  and  ceilings  surprises  the 
traveller  in  climates  warmer  than  our  own."  The  "Elgin  Sand- 
stones" have  also  yielded  another  Lizard,  which  was  originally 
described  by  Professor  Huxley  under  the  name  of  Hyperoda- 
pcdon,  the  remains  of  the  same  genus  having  been  subsequently 
discovered  in  Triassic  strata  in  India  and  South  Africa.  Tne 
Lizards  of  this  group  must  therefore  have  at  one  time  enjoyed 
a  very  wide  distribution  over  the  globe  ;  and  the  living  Spheno- 
don  of  New  Zealand  is  believed  by  Professor  Huxley  to  be  the 
nearest  living  ally  of  this  family.  The  Hyperodapedon  of  the 
Elgin  Sandstones  was  about  six  feet  in  length,  with  limbs 
adapted  for  terrestrial  progression,  but  with  the  bodies  of  the 
vertebrte  slightly  biconcave,  and  having  two  rows  of  palatal 
teeth,  which  become  worn  down  to  the  bone  in  old  age. 
Lastly,  the  curious  Rhynchosaurus  of  the  Trias  is  also  referred, 
by  the  eminent  comparative  anatomist  above  mentioned,  to  the 
order  of  the  Lizards.  In  this  singular  reptile  (fig.  151)  the  skull 

is  somewhat  bird-like,  and  the 
jaws  appear  to  have  been  desti- 
tute of  teeth,  and  to  have  been 
encased  in  a  horny  sheath  like 
the  beak  of  a  Turtle  or  a  Bird. 
It  is  possible,  however,  that  the 
palate  was  furnished  with  teeth. 
The  group  of  the  Crocodiles 
and  Alligators  (Crocodilia],  dis- 
tinguished by  the  fact  that  the  teeth  are  implanted  in  dis- 
tinct sockets  and  the  skin  more  or  less  extensively  provided 
with  bony  plates,  is  represented  in  the  Triassic  rocks  by  the 
Stagonolepis  of  the  Elgin  Sandstones.  The  so-called  "Theco- 
dont"  reptiles  (such  as  Belodon,  Thecodontosaums,  and  Palao- 
saurus,  fig.  152,  c,  d,  e)  are  also  nearly  related  to  the  Croco- 
diles, though  it  is  doubtful  if  they  should  be  absolutely  referred 
to  this  group.  In  these  reptiles,  the  teeth  are  implanted  in 
distinct  sockets  in  the  jaws,  their  crowns  being  more  or  less 
compressed  and  pointed,  "  with  trenchant  and  finely  serrate 
margins  "  (Owen).  The  bodies  of  the  vertebrae  are  hollowed 
out  at  both  ends,  but  the  limbs  appear  to  be  adapted  for  pro- 
gression on  the  land.  The  genus  Belodon  (fig.  152,  c]  is 
known  to  occur  in  the  Keuper  of  Germany  and  in  America ; 


THE   TRIASSIC   PERIOD. 


2I9 


and  Palceosaurus  (fig.  153,  e)  has  also  been  found  in  the  Trias 
of  the  same  region.  Teeth  of  the  latter,  however,  are  found, 
along  with  remains  of  Thecodontosaurus  (fig,  153,  d\  in  a 
singular  magnesian  conglomerate  near  Bristol,  which  was 
originally  believed  to  be  of  Permian  age,  but  which  appears 
to  be  undoubtedly  Triassic. 


Fig.  152. — Triassic  Reptiles,  a,  Skull  of  Nothosa-urus  mirabilis,  reduced  in  size — Mus- 
chelkalk,  Germany  ;  b,  Tooth  of  Simosaurus  Gaillardoti,  of  the  natural  size — Muschel- 
kalk,  Germany  ;  c,  Tooth  of Belodon  Carolinensis — Trias,  America;  d,  Tooth  of  Theco- 
dontosaunis  antiquus,  slightly  enlarged — Britain;  ey  Tooth  of  Palceosaurus  platyodon,  of 
the  natural  size— Britain. 

The  Trias  has  also  yielded  the  remains  of  the  great  marine 
reptiles  which  are  often  spoken  of  collectively  as  the  "  Enalio- 
saurians  "  or  "  Sea-lizards/'  and  which  will  be  more  particularly 
spoken  of  iri  treating  of  the  Jurassic  period,  of  which  they  are 
more  especially  characteristic.  In  all  these  reptiles  the  limbs 
are  flattened  out,  the  digits  being  enclosed  in  a  continuous 
skin,  thus  forming  powerful  swimming-paddles,  resembling  the 
" flippers"  of  the  Whales  and  Dolphins  both  in  their  general 
structure  and  in  function.  The  tail  is  also  long,  and  adapted 
to  act  as  a  swimming-organ  ;  and  there  can  be  no  doubt  but 
that  these  extraordinary  and  often  colossal  reptiles  frequented 
the  sea,  and  only  occasionally  came  to  the  land.  The  Triassic 
Enaliosaurs  belong  to  a  group  of  which  the  later  genus 
Plesiosaurus  is  the  type  (the  Sauropterygid).  One  of  the  best 
known  of  the  Triassic  genera  is  Nothosaurm  (fig.  152,  a),  in 
which  the  neck  was  long  and  bird-like,  the  jaws  being  im- 
mgnsely  elongated,  and  carrying  numerous  powerful  conical 
teeth  implanted  in  distinct  sockets.  The  teeth  in  Simosaurus 
(152,  b)  are  of  a  similar  nature ;  but  the  orbits  are  of  enormous 
size,  indicating  eyes  of  corresponding  dimensions,  and  perhaps 
pointing  to  the  nocturnal  habits  of  the  animal.  In  the  singular 


220  HISTORICAL   PAL/EONTOLOGY. 

Placodus,  again,  the  teeth  are  in  distinct  sockets,  but  resemble 
those  of  many  fishes  in  being  rounded  and  obtuse  (fig.  153), 

forming  broad  crushing  plates 
adapted  for  the  comminu- 
tion of  shell-fish.  There  is  a 
row  of  these  teeth  all  round 
the  upper  jaw  proper,  and  a 
double  series  on  the  palate, 
but  the  lower  jaw  has  only  a 
single  row  of  teeth.  Placodus 
is  found  in  the  Muschelkaik, 
and  the  characters  of  its  den- 
tal apparatus  indicate  that 
it  was  much  more  peaceful 
in  its  habits  than  us  asso 

chelkalk,  Germany.  CiatCS    the    NotllOSaUr    and  Sl- 

mosaur. 

The  Triassic  rocks  of  South  Africa  and  India  have  yielded 
the  remains  of  some  extraordinary  Reptiles,  which  have  been 
placed  by  Professor  Owen  in  a  separate  order  under  the  name 
of  Anomodontia.  The  two  principal  genera  of  this  group  are 
Dicynodon  and  Oudenodon,  both  of  which  appear  to  have  been 
large  Reptiles,  with  well-developed  limbs,  organised  for  pro- 
gression upon  the  dry  land.  In  Oudenodon  (fig.  154,  B)  the 
jaws  seem  to  have  been  wholly  destitute  of  teeth,  and  must 
have  been  encased  in  a  horny  sheath,  similar  to  that  with 
which  we  are  familiar  in  the  beak  of  a  Turtle.  In  Dicynodon 
(fig.  154,  A),  on  the  other  hand,  the  front  of  the  upper  jaw 
and  the  whole  of  the  lower  jaw  were  destitute  of  teeth,  and 
the  front  of  the  mouth  must  have  constituted  a  kind  of  beak; 
but  the  upper  jaw  possessed  on  each  side  a  single  huge  conical 
tusk,  which  is  directed  downwards,  and  must  have  continued 
to  grow  during  the  life  of  the  animal. 

It  may  be  mentioned  that  the  above-mentioned  Triassic 
sandstones  of  South  Africa  have  recently  yielded  to  the  re- 
searches of  Professor  Owen  a  new  and  unexpected  type  of 
Reptile,  which  exhibits  some  of  the  structural  peculiarities 
which  we  have  been  accustomed  to  regard  as  characteristic 
of  the  Carnivorous  quadrupeds.  The  Reptile  in  question  has 
been  -named  Cynodraco,  and  it  is  looked  upon  by  its  distin- 
guished discoverer  as  the  type  of  a  new  order,  to  which  he  foas 
given  the  name  of  Theriodontia.  The  teeth  of  this  singular 
form  agree  with  those  of  the  Carnivorous  quadrupeds  in  con- 
sisting of  three  distinct  groups — namely,  front  teeth  or  incisors, 
eye  teeth  or  canines,  and  back  teeth  or  molars.  The  canines 


THE  TRIASSIC    PERIOD. 


221 


also  are  long  and  pointed,  very  much  compressed,  and  having 
their  lateral  margins  finely  serrated,  thus  presenting  a  singular 


Fig.  154. — Triassic  Anomodont  Reptiles.  A,  Skull  of  D  icy  notion  lacerticeps,  showing 
one  of  the  great  maxillary  tusks ;  B,  Skull  of  Oudenodon  Bainii,  showing  the  toothless, 
beak-like  jaws.  From  the  Trias  of  South  Africa.  (After  Owen.) 

resemblance  to  the  teeth  of  the  extinct  "  Sabre-toothed  Tiger" 
(Machairodus).  The  bone  of  the  upper  arm  (humerus)  further 
shows  some  remarkable  resemblances  to  the  same  bone  in  the 
Carnivorous  Mammals.  As  has  been  previously  noticed,  Pro- 
fessor Owen  is  of  opinion  that  some  of  the  Reptilian  remains 
of  the  Permian  deposits  will  also  be  found  to  belong  to  this 
group  of  the  "  Theriodonts." 

Lastly,  we  find  in  the  Triassic  rocks  the  remains  of  Reptiles 
belonging  to  the  great  Mesozoic  order  of  the  Deinosauria. 
This  order  attains  its  maximum  at  a  later  period,  and  will  be 
spoken  of  when  the  Jurassic  and  Cretaceous  deposits  come  to 
be  considered.  Trie  chief  interest  of  the  Triassic  Reptiles  of 
this  group  arises  from  the  fact  that  they  are  known  by  their 
footprints  as  well  as  by  their  bones  ;  and  a  question  has  arisen 
whether  the  supposed  footprints  of  birds  which  occur  in  the 
Trias  have  not  really  been  produced  by  Deinosaurs.  This 
leads  us,  therefore,  to  speak  at  the  same  time  as  to  the  evi- 
dence which  we  have  of  the  existence  of  the  class  of  Birds 
during  the  Triassic  period.  No  actual  bones  of  any  bird  have 


222 


HISTORICAL   PALEONTOLOGY. 


as  yet  been  detected  in  any  Triassic  deposit :  but  we  have 
tolerably  clear  evidence  of  their  existence  at  this  time  in  the 
form  of  footprints.  The  impressions  in  question  are  found  in 
considerable  numbers  in  certain  red  sandstones  of  the  age  of 
the  Trias  in  the  valley  of  the  Connecticut  River,  in  the  United 
States.  They  vary  much  in  size,  and  have  evidently  been 
produced  by  many  different  animals  walking  over  long 
stretches  of  estuarine  mud  and  sand  exposed  at  low  water. 
The  footprints  now  under  consideration  form  a  double  series 
of  single  prints,  and  therefore,  beyond  all  question,  are  the 
tracks  of  a  biped—  that  is,  of  an  animal  which  walked  upou 
two  legs.  No  living  animals,  save  Man  and  the  Birds,  walk 
habitually  on  two  legs  ;  and  there  is,  therefore,  a  primd  fade 
presumption  that  the  authors  of  these  prints  were  Birds. 
Moreover,  each  impression  consists  of  the  marks  of  three  toes 
turned  forwards  (fig.  155),  and  therefore  are  precisely  such  as 


Fig.  155. — Supposed  footprint  of  a  Bird,  from  the  Triassic  Sandstones  of  the  Con- 
necticut River.     The  slab  shows  also  numerous  "  rain-prints." 

might  be  produced  by  Wading  or  Cursorial  Birds.  Further, 
the  impressions  of  the  toes  show  exactly  the  same  numerical 
progression  in  the  number  of  the  joints  as  is  observable  in 
living  Birds — that  is  to  say,  the  innermost  of  the  three  toes 
consists  of  three  joints,  the  middle  one  of  four,  and  the  outer 
one  of  five  joints.  Taking  this  evidence  collectively,  it  would 
have  seemed,  until  lately,  quite  certain  that  these  tracks  could 
only  have  been  formed  by  Birds.  It  has,  however,  been 
shown  that  the  Deinosaurian  Reptiles  possess,  in  some  cases 
at  any  rate,  some  singularly  bird -like  characters,  amongst 


THE   TRIASSIC   PERIOD. 


223 


which  is  the  fact  that  the  animal  possessed  the  power  of 
walking,  temporarily  at  least,  on  its  hind-legs,  which  were 
much  longer  and  stronger  than  the  fore -limbs,  and  which 
were  sometimes  furnished  with  no  more  than  three  toes. 
As  the  bones  and  teeth  of  Deinosaurs  have  been  found  in 
the  Triassic  deposits  of  Nor.th  America,  it  may  be  regarded  as 
certain  that  some  of  the  bipedal  tracks  originally  ascribed  to 
Birds  must  have  really  been  produced  by  these  Reptiles.  It 
seems  at  the  same  time  almost  a  certainty  that  others  of  the 
three-toed  impressions  of  the  Connecticut  sandstones  were  in 
truth  produced  by  Birds,  since  it  is  doubtful  if  the  bipedal 
mode  of  progression  was  more  than  an  occasional  thing 
amongst  the  Deinosaurs,  and  the  greater  number  of  the 
many  known  tracks  exhibit  no  impressions  of  fore  -  feet. 
Upon  the  whole,  therefore,  we  may,  with  much  probability, 
conclude  that  the  great  class  of  Birds  (Aves)  was  in  existence 
in  the  Triassic  period.  If  this  be  so,  not  only  must  there 
have  been  quite  a  number  of  different  forms,  but  some  of 
them  must  have  been  of  very  large  size.  Thus  the  largest 
footprints  hitherto  discovered  in  the  Connecticut  sandstones 
are  22  inches  long  and  12  inches  wide,  with  a  proportionate 
length  of  stride.  These  measurements  indicate  a  foot  four 
times  as  large  as  that  of  the  African  Ostrich ;  and  the  animal 
which  produced  them— whether  a  Bird  or  a  Deinosaur — must 
have  been  of  colossal  dimensions. 

Finally,  the  Trias  completes  the  tale  of  the  great  classes  of 
the  Vertebrate  sub-kingdom  by  presenting  us  with  remains  of 
the  first  known  of  the  true  Quadrupeds  or  Mammalia,  These 
are  at  present  only  known  by  their  teeth,  or,  in  one  instance, 
by  one  of  the  halves  of  the  lower  jaw  ;  and  these  indicate 
minute  Quadrupeds,  which  present  greater  affinities  with  the 
little  Banded  Ant-eater  (Myrmecobius  fasriatus,  fig.  158)  of 
Australia  than  with  any  other  living  form.  If  this  conjecture 


Fig.  1 56.  — Lower  jaw  of  Droniatherium  sylvestre. 
Trias,  North  Carolina.     (After  Emmons.) 


Fig.  157. — a,  Molar  tooth  of 
Microlestes  antiquns,  magni- 
fied ;  b,  Crown  of  the  same, 
magnified  still  further.  Trias, 
Germany. 


be  correct,  these  ancient  Mammals  belonged  to  the  order  of 
the  Marsupials  or  Pouched  Quadrupeds  (Marsupialia\  which 


224 


HISTORICAL    PAL/EON TOLOGY. 


are  now  exclusively  confined  to  the  Australian  province,  South 
America,  and  the  southern  portion   of  North  America.     In 


Fig.  158. —The  Banded  Ant-eater  (.!/> 


rus  fascia  fat)  of  Australia. 


the  Old  World,  the  only  known  Triassic  Mammals  belong  to 
the  genus  Microlestes,  and  to  the  probably  identical  Hypsi- 
prymnopsis  of  Professor  Boyd  Dawkins.  The  teeth  of  Micro- 
lestes (fig.  157)  were  originally  discovered  by  Plieninger  in 
1847  in  the  "bone-bed"  which  is  characteristic  of  the  sum- 
mit of  the  Rhsetic  series  both  in  Britain  and  on  the  continent 
of  Europe  ;  and  the  known  remains  indicate  two  species.  In 
Britain,  teeth  of  Microlestes  have  been  discovered  by  Mr 
Charles  Moore  in  deposits  of  Upper  Triassic  age,  filling  a 
fissure  in  the  Carboniferous  limestone  near  Frome,  in  Somer- 
setshire ;  and  a  molar  tooth  of  Hypsiprymnopsis  was  found  by 
Professor  Boyd  Dawkins  in  Rhsetic  marls  below  the  "  bone- 
bed  "  at  Watchet,  also  in  Somersetshire.  In  North  America, 
lastly,  there  has  been  found  in  strata  of  Triassic  age  one  of 
the  branches  of  the  lower  jaw  of  a  small  Mammal,  which  has 
been  described  under  the  name  of  Dromatherium  sylvestre 
(fig.  156).  The  fossil  exhibits  ten  small  molars  placed  side 
by  side,  one  canine,  and  three  incisors,  separated  by  small 
intervals,  and  it  indicates  a  small  insectivorous  animal,  pro- 
bably most  nearly  related  to  the  existing  Myrmecobiys. 


LITERATURE. 

The  following  list  comprises  a  few  of  the  more  important  sources  of 
information  as  to  the  Triassic  strata  and  their  fossil  contents  : — 

(1)  -*  Geology  of  Oxford  and  the  Valley  of  the  Thames.'     Phillips. 

(2)  'Memoirs  of  the  Geological  Survey  of  Great  Britain  and  Ireland.' 

(3)  'Report  on  the  Geology  of  Londonderry,'  &c.      Portlock. 


THE    TRIASSIC    PERIOD.  225 

(4)  "On  the  Zone  of  Avicula  contorta,"  &c.  —  'Quart.   Journ.    Geol. 

Soc.,'  vol.  xvi.,  1860.     Dr  Thomas  Wright. 

(5)  "  On  the  Zones  of  the  Lower  Lias  and  the  Avicula  contorta  Zone" 

— 'Quart.  Journ.   Geol.  Soc.,'  vol.  xvii.,  1861.     Charles  Moore. 

(6)  "On  Abnormal  Conditions  of  Secondary  Deposits, ""&c. — 'Quart. 

Journ.  Geol.  Soc.,'  vol.  xxiii. ,  1876-77.     Charles  Moore. 

(7)  '  Geognostische    Beschreibung    des     Bayerischen    Alpengebirges.' 

Giimbel. 

(8)  *  Lethsea  Rossica.'     Pander. 

(9)  '  Lethaea  Geognostica.'  .  Bronn. 

(10)  '  Petrefacta  Germanize.'     Goldfuss. 

( 1 1 )  '  Petrefaktenkunde. '     Quenstedt. 

(12)  'Monograph  of  the  Fossil  Estheriae'  (Pakeontographical  Society). 

Rupert  Jones. 

(13)  "  Fossil  Remains  of  Three  Distinct  Saurian  Animals,  recently  dis- 

covered in  the  Magnesian  Conglomerate  near  Bristol  " — '  Trans. 
Geol.  Soc.,'  ser.  2,  vol.  v.,  1840.     Riley  and  Stutchbury. 

(14)  '  Die  Saurier  des  Muschekalkes.'     Von  Meyer. 

(15)  '  Beitrage   /ur    Palaeontologie    Wiirttembergs.'      Von    Meyer    and 

Plieninger. 

(16)  '  Manual  of  Palaeontology.'     Owen. 

(17)  '  Odontography. '     Owen. 

(18)  '  Report  on  Fossil  Reptiles  '   (British  Association,    1841).     Owen. 

(19)  "  On  Dicynodon " — 'Trans.  Geol.  Soc.,' vol.  iii.,  1845.     Owen. 

(20)  '  Descriptive  Catalogue  of  Fossil  Reptilia  and  Fishes  in  the  Museum 

of  the  Royal  College  of  Surgeons',  England.'     Owen. 

(21)  "  On  Species  of  Labyrinthodon  from' Warwickshire  " — '  Trans.  Geol. 

Soc.,'  ser.  2,  vol.  vi.     Owen. 

(22)  "On   a   Carnivorous    Reptile"   (Cynodraco   major),  £c. — 'Quart. 

Journ.  Geol.  Soc.,'  vol.  xxxii.,  1876.     Owen. 

(23)  "  On  Evidences  of  Theriodonts  in  Permian  Deposits,"  &c. — '  Quart. 

Journ.  Geol.  Soc.,'  vol.  xxxii.,  1876.     Owen. 

(24)  "On   the    Stagonolepis   Robertsoni,"  &c.  —  'Quart.  Journ.   Geol. 

Soc.,'  vol.  xv.,  1859.     Huxley. 

(25)  "  On  a  New  Specimen  of  Telerpeton  Elginense  " — '  Quart.  Journ. 

Geol.  Soc.,'  vol.  xxiii.,  1866.     Huxley. 

(26)  "On  Hyperodapedon " — 'Quart.    Journ.    Geol.    Soc.,'  vol.    xxv., 

1869.     Huxley. 

(27)  "On  the  Affinities  between  the  Deinosaurian  Reptiles  and  Birds" 

—  'Quart.  Journ.  Geol.  Soc.,'  vol.  xxvi.,  1870.     Huxley. 

(28)  "On  the  Classification  of  the  Deinosauria,"  &c. —  'Quart.  Journ. 

Geol.  Soc.,'  vol.  xxvi.,  1870.     Huxley. 

(29)  "  Palseontologica  Indica  "— '  Memoirs  of  the  Geol.  Survey  of  India. ' 

(30)  "  On  the  Geological  Position  and  Geographical  Distribution  of  the 

Dolomitic  Conglomerate  of  the  Bristol  Area" — 'Quart.  Journ. 
Geol.  Soc.,'  vol.  xxvi.,  1870.     R.  Etheridge,  sen. 

(31)  "  Remains  of  Labyrinthodonta  from  the  Keuper  Sandstone  of  War- 

wick " —  'Quart.  Journ.  Geol.  Soc.,'  vol.  xxx.,  1874.     Miall. 

(32)  '  Manual  of  Geology.'     Dana. 

(33)  'Synopsis  of  Extinct  Batrachia  and   Reptilia  of  North  America.' 

Cope. 

(34)  'Fossil  Footmarks.'     Hitchcock. 

(35)  'Ichnology  of  New  England.'     Hitchcock. 

(36)  'Traite  de  Paleontologie  Vegetale.'     Schimper. 

(37)  'Histoire  des  Vegetaux  Fossiles. '     Brongniart. 

(38)  '  Monographic  der  Fossilen  Conifercn.'     Gceppert. 


226  HISTORICAL   PALEONTOLOGY. 

CHAPTER   XVI. 
THE  JURASSIC  PERIOD. 

Resting  upon  the  Trias,  with  perfect  conformity,  and  with 
an  almost  undeterminable  junction,  we  have  the  great  series  of 
deposits  which  are  known  as  the  Oolitic  Rocks,  from  the  com- 
mon occurrence  in  them  of  oolitic  limestones,  or  as  the  Juras- 
sic Rocks,  from  their  being  largely  developed  in  the  mountain^ 
range  of  the  Jura,  on  the  western  borders  of  Switzerland. 
Sediments  of  this  series  occupy  extensive  areas  in  Great  Britain, 
on  the  continent  of  Europe,  and  in  India.  In  North  America, 
limestones  and  marls  of  this  age  have  been  detected  in  "  the 
Black  Hills,  the  Laramie  range,  and  other  eastern  ridges  of  the 
Rocky  Mountains  ;  also  over  the  Pacific  slope,  in  the  Uintah, 
Wahsatch,  and  Humboldt  Mountains,  and  in  the  Sierra  Ne- 
vada "  (Dana) ;  but  in  these  regions  their  extent  is  still  un- 
known, and  their  precise  subdivisions  have  not  been  deter- 
mined. Strata  belonging  to  the  Jurassic  period  are  also  known 
to  occur  in  South  America,  in  Australia,  and  in  the  Arctic 
zone.  When  fully  developed,  the  Jurassic  series  is  capable  of 
subdivision  into  a  number  of  minor  groups,  of  which  some  are 
clearly  distinguished  by  their  mineral  characters,  whilst  others 
are  separated  with  equal  certainty  by  the  differences  of  the 
fossils  that  they  contain.  It  will  be  sufficient  for  our  present 
purpose,  without  entering  into  the  more  minute  subdivisions 
of  the  series,  to  give  here  a  very  brief  and  general  account 
of  the  main  sub-groups  of  the  Jurassic  rocks,  as  developed  in 
Britain — the  arrangement  of  the  Jura-formation  of  the  continent 
of  Europe  agreeing  in  the  main  with  that  of  England. 

I.  THE  LIAS. — The  base  of  the  Jurassic  series  of  Britain 
is  formed  by  the  great  calcareo  -  argillaceous  deposit  of  the 
"Lias,"  which  usually  rests  conformably  and  almost  inseparably 
upon  the  Rhsetic  beds  (the  so-called  "White  Lias"),  and 
passes  up,  generally  conformably,  into  the  calcareous  sand- 
stones of  the  Inferior  Oolite.  The  Lias  is  divisible  into  the 
three  principal  groups  of  the  Lower,  Middle,  and  Upper  Lias, 
as  under,  and  these  in  turn  contain  many  well-marked  "zones;" 
so  that  the  Lias  has  some  claims  to  be  considered  as  an  inde- 
pendent formation,  equivalent  to  all  the  remaining  Oolitic 
rocks.  The  Lower  Lias  (Terrain  Sincmurieti  of  D'Orbigny) 
sometimes  attains  a  thickness  of  as  much  as  600  feet,  and  con- 
sists of  a  great  series  of  bluuh  or  greyish  laminated  clays, 


THE   JURASSIC    PERIOD. 

alternating  with  thin  bands  of  blue  or  grey  limestone — the 
whole,  when  seen  in  quarries  or  cliffs  from  a  little  distance, 
assuming  a  characteristically  striped  and  banded  appearance. 
By  means  of  particular  species  of  Ammonites,  taken  along  with 
other  fossils  which  are  confined  to  particular  zones,  the  Lower 
Lias  may  be  subdivided  into  several  well-marked  horizons. 
The  Middle  Lias,  or  Marlstone  Scries  (Terrain  Liasien  of 
D'Orbigny),  may  reach  a  thickness  of  200  feet,  and  consists  of 
sands,  arenaceous  marls,  and  argillaceous  limestones,  sometimes 
with  ferruginous  beds.  The  Upper  Lias  ( Terrain  Toarden  of 
D'Orbigny)  attains  a  thickness  of  300  feet,  and  consists  princi- 
pally of  shales  below,  passing  upwards  into  arenaceous  strata. 

II.  THE  LOWER  OOLITES. — Above  the  Lias  comes  a  com- 
plex series  of  partly  arenaceous   and    argillaceous,  but  prin- 
cipally calcareous  strata,  of  which  the  following  are  the  more 
important    groups  :   a,  The  Inferior  Oolite  (Terrain  Bajocien 
of  D'Orbigny),   consisting   of  more  than   200  feet  of  oolitic 
limestones,  sometimes  more   or  less  sandy ;   b,  The  Fullers 
Earth,  a  series  of  shales,  clays,  and  marls,  about  120  feet  in 
thickness;  c,  The  Great  Oolite  or  Bath  Oolite  (Terrain  Bat h- 
onien  of  D'Orbigny),   consisting  principally   of  oolitic   lime- 
stones, and  attaining  a  thickness  of  about  130  feet.     The  well- 
known  "  Stonesfield  Slates"  belong  to  this  horizon;  and  the 
locally  developed  "  Bradford  Clay,"  "  Cornbrash,"  and  "  For- 
est-marble "  may  be  regarded  as   constituting  the  summit  of 
this  group. 

III.  THE  MIDDLE  OOLITES. — The  central    portion   of  the 
Jurassic  series  of  Britain  is  formed  by  a  great  argillaceous  de- 
posit, capped  by  calcareous  strata,  as  follows  :  a,  The  Oxford 
Clay  (Terraiti  Callovien  and  Terrain  Oocfordien  of  D'Orbigny), 
consisting  of  dark-coloured  laminated  clays,  sometimes  reach- 
ing a  thickness  of  700  feet,  and  in  places  having  its  lower  por- 
tion developed  into  a  hard  calcareous  sandstone  ("  Kelloway 
Rock");  b,  The   Coral-Rag  (Terrain  Corallien  of  D'Orbigny, 
"Nerinean  Limestone"  of  the  Jura,  "  Diceras  Limestone"  of 
the  Alps),  consisting,  when  typically  developed,  of  a  central 
mass  of  oolitic  limestone,  underlaid  and  surmounted  by  cal- 
careous grits. 

IV.  THE   UPPER   OOLITES. — a,  The   base   of  the   Upper 
Oolites  of  Britain  is  constituted  by  a  great  thickness  (600  ieet 
or  more)  of  laminated,  sometimes  carbonaceous  or  bituminous 
clays,  which  are  known  as  the  Kimmeridge  Clay  (Terrain  Kim- 
meridgien  of  D'Orbigny);  b,  The  Portland  Beds  (Terrain  Port- 
landien  of  D'Orbigny)  succeed  the  Kimmeridge  clay,  and  con- 
sist inferiorly  of  sandy  beds  surmounted  by  oolitic  limestones 


228  HISTORICAL   PALEONTOLOGY. 

("  Portland  Stone"),  the  whole  series  attaining  a  thickness  of 
150  feet  or  more,  and  containing  marine  fossils;  t,  The  Pur- 
beck  Beds  are  apparently  peculiar  to  Great  Britain,  where  they 
form  the  summit  of  the  entire  Oolitic  series,  attaining  a  total 
thickness  of  from  150  to  200  feet.  The  Purbeck  beds  consist 
of  arenaceous,  argillaceous,  and  calcareous  strata,  which  can 
be  shown  by  their  fossils  to  consist  of  a  most  remarkable  alter- 
nation of  fresh-water,  brackish-water,  and  purely  marine  sedi- 
ments, together  with  old  land-surfaces,  or  vegetable  soils,  which 
contain  the  upright  stems  of  trees,  and  are  locally  known  as 
"  Dirt-beds." 

One  of  the  most  important  of  the  Jurassic  deposits  of  the 
continent  of  Europe,  which  is  believed  to  be  on  the  horizon 
of  the  Coral-rag  or  of  the  lower  part  of  the  Upper  Oolites,  is 
the  "  Solenhofen  Slate"  of  Bavaria,  an  exceedingly  fine-grained 
limestone,  which  is  largely  used  in  lithography,  and  is  cele- 
brated for  the  number  and  beauty  of  its  organic  remains,  and 
especially  for  those  of  Vertebrate  animals. 

The  subjoined  sketch-section  (fig.  159)  exhibits  in  a  dia- 
grammatic form  the  general  succession  of  the  Jurassic  rocks  of 
Britain. 

Regarded  as  a  whole,  the  Jurassic  formation  is  essentially 
marine  ;  and  though  remains  of  drifted  plants,  and  of  insects 
and  other  air-breathing  animals,  are  not  uncommon,  the  fossils 
of  the  formation  are  in  the  main  marine.  In  the  Purbeck 
series  of  Britain,  anticipatory  of  the  great  river-deposit  of  the 
Wealden,  there  are  fresh-water,  brackish-water,  and  even  terres- 
trial strata,  indicating  that  the  floor  of  the  Oolitic  ocean  was 
undergoing  upheaval,  and  that  the  marine  conditions  which 
had  formerly  prevailed  were  nearly  at  an  end.  In  places 
also,  as  in  Yorkshire  and  Sutherlandshire,  are  found  actual 
beds  of  coal  :  but  the  great  bulk  of  the  formation  is  an  indu- 
bitable sea-deposit ;  and  its  limestones,  oolitic  as  they  com- 
monly are,  nevertheless  are  composed  largely  of  the  commin- 
uted skeletons  of  marine  animals.  Owing  to  the  enormous 
number  and  variety  of  the  organic  remains  which  have  been 
yielded  by  the  richly  fossiliferous  strata  of  the  Oolitic  series, 
it  will  not  be  possible  here  to  do  more  than  to  give  an  outline- 
sketch  of  the  principal  forms  of  life  which  characterise  the 
Jurassic  period  as  a  whole.  It  is  to  be  remembered,  however, 
that  every  minor  group  of  the  Jurassic  formation  has  its  own 
peculiar  fossils,  and  that  by  the  labours  of  such  eminent  ob- 
servers as  Quenstedt,  Oppel,  D'Orbigny,  Wright,  De  la  Beche, 
Tate,  and  others,  the  entire  series  of  Jurassic  sediments  admits 
of  a  more  complete  and  more  elaborate  subdivision  into  zones 


THE  JURASSIC   PERIOD. 


229 


characterised  by  special  life-forms  than  has  as  yet  been  found 
practicable  in  the  case  of  any  other  rock-series. 


GENERALISED  SECTION  OF  THE  JURASSIC  ROCKS 
OF  ENGLAND. 


-Purbeck  Beds. 


Portland  Beds. 


Kimmeridge  Clay. 


Coral- Rag. 


Oxford  Clay. 


-Cornbrash  and  Forest-marble. 
-Great  Oolite. 

--Fuller's  Earth. 
-Inferior  Oolite. 


Upper  Lias. 

Middle   Lias   (Marlstone 

series). 

Lower  Lius. 


Rhsetic     Marls     ("  White 
Lias  "). 


The  plants  of  the    Jurassic    period    consist   principally  of 
Ferns,  Cycads,  and  Conifers — agreeing  in  this  respect,  there- 


230  HISTORICAL   PALEONTOLOGY. 

fore,  with  those  of  the  preceding  Triassic  formation.  The 
Ferns  are  very  abundant,  and  belong  partly  to  old  and  partly 
to  new  genera.  The  Cycads  are  also  very  abundant,  and,  on 
the  whole,  constitute  the  most  marked  feature  of  the  Jurassic 
vegetation,  many  genera  of  this  group  being  known  (Ptero- 
phyllum,  Otozamites,  Zamites,  Crossozatnia,  Williamsonia,  Buck- 
landia,  &c.)  The  so-called  "dirt-bed"  of  the  Purbeck  series 
consists  of  an  ancien  soil,  in  which  stand  erect  the  trunks  of 
Conifers  and  the  silicified  stools  of  Cycads  of  the  genus  Mantcl- 
//rt  (fig.  1 60).  The  Conifera  of  the  Jurassic  are  represented  by 


Fig.  160. — Mantellla  (Cycadeoideti)  megaJoj>hyUa,  a  Cycad  from  the  Purbeck 
"dirt-bed  "     Upper  Oolites,  England. 

various  forms  more  or  less  nearly  allied  to  the  existing  Arau- 
caricz ;  and  these  are  known  not  only  by  their  stems  or 
branches,  but  also  in  some  cases  by  their  cones.  We  meet, 
also,  with  the  remains  of  undoubted  Endogenous  plants,  the 
most  important  of  which  are  the  fruits  of  forms  allied  to  the 
existing  Screw-pines  (Pandan&z},  such  as  Podocarya  and  Kaida- 
carpum.  So  far,  however,  no  remains  of  Palms  have  been 
found ;  nor  are  we  acquainted  with  any  Jurassic  plants  which 
could  be  certainly  referred  to  the  great  "  Angiospermous " 
group  of  the  Exogens,  including  the  majority  of  our  ordinary 
plants  and  trees. 

Amongst  animals,  the  Protozoans  are  well  represented  in 
the  Jurassic  deposits  by  numerous  Foraminifers  and  Sponges ; 
as  are  the  C&lenterates  by  numerous  Corals.  Remains 
of  these  last-mentioned  organisms  are  extremely  abundant 
in  some  of  the  limestones  of  the  formation,  such  as  the 
"  Coral-rag"  and  the  Great  Oolite ;  and  the  former  of  these 
may  fairly  be  considered  as  an  ancient  "  reef/'  The  Rugose 
Corals  have  not  hitherto  been  detected  in  the  Jurassic  rocks  ; 
and  the  "  Tabulate  Corals"  so-called,  are  represented  only  by 
examples  of  the  modern  genus  MiUeponi.  With  this  excep- 


THE   JURASSIC   PERIOD.  231 

tion,  all  the  Jurassic  Corals  belong  to  the  great  group  which 
predominates  in  recent  seas  (Zoantharia  sderodermata);  and 
the  majority  belong  to  the  important  reef-building  family  of 
the  "  Star-corals  "  (Astrceidtz),  The  form  here  figured  (Thecos- 
milia  annular  is,  fig.  161)  is  one  of  the  characteristic  species 
of  the  Coral-rag. 


Fig.  161. — Thecosmilia  annularis.     Coral-rag,  England. 

The  Echinoderms  are  very  numerous  and  abundant  fossils 
in  the  Jurassic  series,  and  are  represented  by  Sea-lilies,  Sea- 
urchins,  Star-fishes,  and  Brittle-stars.  The  Crinoids  are  still 
common,  and  some  of  the  limestones  of  the  series  are  largely 
composed  of  the  debris  of  these  organisms.  Most  of  the 
Jurassic  forms  resemble  those  with  which  we  are  already 
familiar,  in  having  the  body  permanently  attached  to  some 
foreign  object  by  means  of  a  longer  or  shorter  jointed  stalk 
or  "  column."  One  of  the  most  characteristic  Jurassic  genera 
of  these  "  stalked  "  Crinoids  (though  not  exclusively  confined 
to  this  period)  is  Pentacrinus  (fig.  162).  In  this  genus,  the 
column  is  five-sided,  with  whorls  of  '"'  side-arms  ; "  and  the  arms 
are  long,  slender,  and  branched.  The  genus  is  represented 
at  the  present  day  by  the  beautiful  "  Medusa-head  Pentacrin- 
ite  "  (Pentacrimis  capiit-medusa).  Another  characteristic  Oolitic 
genus  \<$>Apiocrinus,  comprising  the  so-called  "Pear  Encrinites." 
In  this  group  the  column  is  long  and  rounded,  with  a  dilated 
base,  and  having  its  uppermost  joints  expanded  so  as  to  form, 
with  the  cup  itself,  a  pear-shaped  mass,  from  the  summit  of 
which  spring  the  comparatively  short  arms.  Besides  the 


232 


HISTORICAL  PALAEONTOLOGY. 


"  stalked  "  Crinoids,  the  Jurassic  rocks  have  yielded  the  re- 
mains of  the   higher  group  of  the  "  free  ;;  Crinoids,  such   as 


Fig.  162.—  Pentacrinns  fascicu'.osns,  Lias.  The  left-hand  figure  shows  a  few  of  the 
joints  of  the  column  ;  the  middle  figure  shows  the  arms,  and  the  summit  of  the  column 
with  its  side-arms ;  and  the  right-hand  figure  shows  the  articulating  surface  of  one  of  the 
column-joints. 

Saccosoma.      These   forms   resemble   the    existing    "Feather- 
stars"   (Comatitla)  in  being   attached  when   young  to  some 


THE  JURASSIC    PERIOD.  233 

foreign  body  by  means  of  a  jointed  stem,  from  which  they 
detach  themselves  when  fully  grown  to  lead  an  independent 
existence.  In  this  later  stage  of  their  life,  therefore,  they 
closely  resemble  the  Brittle-stars  in  appearance.  True  Star- 
fishes (Asteroids]  and  Brittle-stars  (Ophiuroids)  are  abundant 
in  the  Jurassic  rocks,  and  the  Sea-urchins  (Echinoids)  are  so 
numerous  and  so  well  preserved  as  to  constitute  quite  a  marked 
feature  of  some  beds  of  the  series.  All  the  Oolitic  urchins 
agree  with  the  modern  Echinoids  in  having  the  shell  composed 
of  no  more  than  twenty  rows  of  plates.  Many  different  genera 
are  known,  and  a  characteristic  species  of  the  Middle  Oolites 
(Hemiridaris  cremilaris,  fig.  163)  is  here  figured. 


Fig.  163. — Kemicidarts  cremilaris,  showing  the  great  tubercles  on  which  the 
spines  were  supported.     Middle  Oolites. 

Passing  over  the  Annelides,  which,  though  not  uncommon, 
are  of  little  special  interest,  we  come  to  the  Articulates,  which 
also  require  little  notice.  Amongst  the  Crustaceans,  whilst  the 
little  Water-fleas  (Ostracoda)  are  still  abundant,  the  most  mark- 
ed feature  is  the  predominance  which  is  now  assumed  by  the 
Decapods — the  highest  of  the  known  groups  of  the  class.  True 
Crabs  (Brachyurd)  are  by  no  means  unknown ;  but  the  prin- 
cipal Oolitic  Decapods  belonged  to  the  "  Long-tailed  "  group 
(Macrura\  of  which  the  '  existing  Lobsters,  Prawns,  and 
Shrimps  are  members.  The  fine-grained  lithographic  slates  of 
Solenhofen  are  especially  famous  as  a  depot  for  the  remains 
of  these  Crustaceans,  and  a  characteristic  species  from  this 
locality  (Eryon  arctiformis,  fig.  164)  is  here  represented. 
Amongst  the  air-breathing  Articulates,  we  meet  in  the  Oolitic 
rocks  with  the  remains  of  Spiders  (Arachnida\  Centipedes 
(Myriapoda),  and  numerous  true  Insects  (Insecta\  In  con- 
nection with  the  last-mentioned  of  these  groups,  it  is  of  interest 
to  note  the  occurrence  of  the  oldest  known  fossil  Butterfly 
— the  Paltzontina  Oolitica  of  the  Stonesfield  slate — the  rela- 


234 


HISTORICAL    PALEONTOLOGY. 


tionships    of  which   appear   to  be  with    some   of  the   living 
Butterflies  of  Tropical  America. 

Coming   to    the   Molhisca,   the   Polyzoaus,    numerous    and 


Fig.  164.— Eryon  arctiformls,  a  "Long-tailed  Decapod,"  from  the  Middle 
Oolites  (Solenhofen  Slate). 

beautiful  as  they  are,  must  be  at  once  dismissed;  but  the 
Brachiopods  deserve  a  moment's  attention.  The  Jurassic 
Lamp-shells  (fig.  165)  do  not  fill  by  any  means  such  a  pre- 
dominant place  in  the  marine  fauna  of  the  period,  as  in  many 
Palaeozoic  deposits,  but  they  are  still  individually  numerous. 
The  two  ancient  genera  Leptana  (fig.  165,  a)  and  Spirifera  (fig. 
165,  £),  dating  the  one  from  the  Lower  and  the  other  from  the 
Upper  Silurian,  appear  here  for  the  last  time  upon  the  scene, 
but  they  have  not  hitherto  been  recognised  in  deposits  later 
than  the  Lias.  The  great  majority  of  the  Jurassic  Brachiopods, 
however,  belong  to  the  genera  Terebratula  (fig.  165,  c,  e,  /} 
and  Rhynchonella  (fig.  165,  d\  both  of  which  are  represented 
by  living  forms  at  the  present  day.  The  Tcrebratute,  in  par- 
ticular, are  very  abundant,  and  the  species  are  often  confined 
to  special  horizons  in  the  series. 

Remains  of  Bivalves  (Lamellibranchiata)  are  very  numerous 


THE  JURASSIC    PERIOD. 


235 


in  the  Jurassic  deposits,  and  in  many  cases  highly  character- 
istic.    In  the  marine  beds  of  the  Oolites,  which  constitute  by 


Fig.  165. — Jurassic  Brachiopods.  «,  Leptcena  Liassica,  enlarged,  the  small  cross  below 
the  figure  indicating  the  'true  size  of  the  shell — Lias ;  b,  Spirifera  rostrata,  Lias ;  c, 
Terebratula^  quadrifida,  Lias  ;  d,  d',  Rhynchonella  varians,  Fuller's  Earth  and  Kello- 
way  Rock  ;  e,  Terebratula  spha-roidalis,  Inferior  Oolite  ;/,  Terebratula  digona,  Brad- 
ford Clay,  Forest-marble,  and  Great  Oolite.  (After  Davidson). 

far  the  greater  portion  of  the  whole  formation,  the  Bivalves 
are  of  course  marine,  and  belong  to  such  genera  as  Trigonia, 
Lima,  Pholadomya,  Cardinia,  Avicula,  Hippopodium,  &c.  j  but 
in  the  Purbeck  beds,  at  the  summit  of  the  series,  we  find 
bands  of  Oysters  alternating  with  strata  containing  fresh-water 
or  brackish-water  Bivalves,  such  as  Cyrence  and  Corbulce.  The 
predominant  Bivalves  of  the  Jurassic,  however,  are  the  Oysters, 
which  occur  under  many  forms,  and  often  in  vast  numbers, 
particular  species  being  commonly  restricted  to  particular 
horizons.  Thus  of  the  true  Oysters,  Ostrea  distorta  is  char- 
acteristic of  the  Purbeck  series,  where  it  forms  a  bed  twelve 
feet  in  thickness,  known  locally  as  the  "  Cinder-bed  ; "  Ostrea 
expansa  abounds  in  the  Portland  beds ;  Ostrea  deltoidea  is 
characteristic  of  the  Kimmeridge  clay ;  Ostrea  gregaria  pre- 
dominates in  the  Coral-rag  ;  Ostrea  acuminata  characterises  the 
small  group  of  the  Fuller's  Earth ;  whilst  the  plaited  Ostrea 
Marshii  (fig.  166)  is  a  common  shell  in  the  Lower  and  Middle 
Oolites.  Besides  the  more  typical  Oysters,  the  Oolitic  rocks 
abound  in  examples  of  the  singularly  unsymmetrical  forms 


236 


HISTORICAL   PALEONTOLOGY. 


belonging  to  the  genera  Exogyra  and  Gryph&a  (fig.  167).     In 
the  former   of  these   are   included    Oysters   with   the   beaks 


Fig.  it>6.~~Ostrea  Marshii.     Middle 
and  Lower  Oolites. 


Fig.  167. - 


«;  ra.     Lias. 


"  reversed  " — that  is  to  say,  turned  towards  the  hinder  part  of 
the  shell ;  whilst  in  the  latter  are  Oysters  in  which  the  lower 
valve  of  the  shell  is  much  the  largest,  and  has  a  large  incurved 
beak,  whilst  the  upper  valve  is  small  and  concave.  One  of 
the  most  characteristic  Exogyra  is  the  E.  virgula  of  the  Oxford 
Clay,  and  of  the  same  horizon  on  the  Continent ;  and  the 
Gryphaa  incurva  (fig.  i67)Js  equally  abundant  in,  and  char- 
acteristic of,  the  formation  of  the  Lias.  Lastly,  we  may 
notice  the  extraordinary  shells  belonging  to  the  genus  Diceras 
(fig.  1 68),  which  are  exclusively  confined  to  the  Middle 

Oolites.  In  this  formation  in 
the  Alps  they  occur  in  such 
abundance  as  to  give  rise  to 
the  name  of  "  Calcaire  a  Di- 
cerates,"  applied  to  beds  of 
the  same  age  as  the  Coral- 
rag  of  Britain.  The  genus  Di- 
ceras belongs  to  the  same  fam- 
ily as  the  "  Thorny  Clams" 
( Chamci)  of  the  present  day — 
the  shell  being  composed  of 
nearly  equally-sized  valves,  the 
beaks  of  which  are  extremely 
prominent  and  twisted  into  a 

spiral.  The  shell  was  attached  to  some  foreign  body  by  the 
beak  of  one  of.  its  valves. 

Amongst  the  Jurassic  Univalves  (Gasteropoda]  there  are 
many  examples  of  the  ancient  and  long-lived  Pleurotomaria  ; 
but  on  the  whole  the  Univalves  begin  to  have  a  modern 
aspect.  The  round-mouthed  ("  holostomatous "),  vegetable- 


Fig.  168. — Diceras  arietina. 
Oolite. 


Middle 


THE   JURASSIC   PERIOD. 


237 


eatiog  Sea-snails,  such  as  the  Limpets  (fatdlitfce),  the  Nerites 
(Nerita),  the  Turritella,  Cheinnitzite,  &c.,  still  hold  a  predomi- 
nant place.  The  two  most  noticeable  genera  of  this  group 
are  Cerithiiim  and  Nerinaa  —  the  former  of  these  attaining 
great  importance  in  the  Tertiary  and  Recent  seas,  whilst  the 
latter  (fig.  169)  is  highly  characteristic  of  the  Jurassic  series, 
though  not  exclusively  confined  to 
it.  One  of  the  limestones  of  the 
Jura,  believed  to  be  of  the  age  of 
the  Coral-rag  (Middle  Oolite)  of  Bri- 
tain, abounds  to  such  an  extent  in 
the  turreted  shells  of  Nerincea  as  to 
have  gained  the  name  of  "  Calcaire 
a  Nerine'es."  In  addition  to  forms 
such  as  the  preceding,  we  now  for 
the  first  time  meet,  in  any  force, 
with  the  Carnivorous  Univalves,  in 
which  the  mouth  of  the  shell  is 
notched  or  produced  into  a  canal, 
giving  rise  to  the  technical  name 
of  "  siphonostomatous,"  applied  to 
the  shell.  Some  of  the  carnivorous 
forms  belong  to  extinct  types,  such 
as  the  Purpuroidea  of  the  Great  Oo- 
lite ;  but  others  are  referable  to  well-known  existing  genera. 
Thus  we  meet  here  with  species  of  the  familiar  groups  of  the 
Whelks  (Buccinum),  the  Spindle  -  shells  (Fusus),  the  Spider- 
shells  (Pteroceras],  Murex,  Rostellaria,  and  others  which  are 
not  at  present  known  to  occur  in  any  earlier  formation. 

Amongst  the  Wing-shells  (Fieropodd},  it  is  sufficient  to  mark 
the  final  appearance  in  the  Lias  of  the  ancient  genus  Comdaria. 

Lastly,  the  order  of  the  Cephalopoda,  in  both  its  Tetrabran- 
chiate  and  Dibranchiate  sections,  undergoes  a  vast  devel- 
opment in  the  Jurassic  period.  The  old  and  comparatively 
simple  genus  Nautilus  is  still  well  represented,  one  species 
being  very  similar  to  the  living  Pearly  Nautilus  (N.  pompihus); 
but  the  Orthocerata  and  Goniatites  of  the  Trias  have  finally 
disappeared;  and  the  great  majority  of  the  Tetrabranchiate 
forms  are  referable  to  the  comprehensive  genus  Ammonites, 
with  its  many  sub-genera  and  its  hundreds  of  recorded  species. 
The  shell  in  Ammonites  is  in  the  form  of  a  flat  spiral,  all  the 
coils  of  which  are  in  contact  (figs.  170  and  171).  The  inner- 
most whorls  of  the  shell  are  more  or  less  concealed ;  and  the 
body-chamber  is  elongated  and  narrow,  rather  than  expanded 
towards  the  mouth.  The  tube  or  siphuncle  which  runs  through 
'17 


Fig.  169.— AVr/«<ZYZ  Goodhallii, 
one-fourth  of  the  natural  size.  The 
left-hand  figure  shows  the  appear- 
ance presented  by  the  shell  when 
vertically  divided.  Coral -rag, 
England. 


HISTORICAL   PALEONTOLOGY. 


the  air-chambers  is  placed  on  the  dorsal  or  convex  side  of  the 
shell;  but  the  principal  character  which  distinguishes  Amman- 


Fig.  170.— Ammonites  Humphresiamis.     Inferior  Oolite. 

ites  from  Goniatites  and  Ceratites  is  the  wonderfully  complex 
manner  in  which  the  septa,  or  partitions  between  the  air-cham- 
bers, are  folded  and  undulated.  To  such  an  extent  does  this 
take  place,  that  the  edges  of  the  septa,  when  exposed  by  the 


Fig.  171. — Ammonites  bifrons.     Lias. 

removal  of  the  shell-substance,  present  in  an  exaggerated  man- 
ner the  appearance  exhibited  by  an  elaborately-dressed  shirt- 
frill  when  viewed  edgewise.  The  species  of  Ammonites  range 
from  the  Carboniferous  to  the  Chalk  j  but  they  have  not  been 


THE  JURASSIC    PERIOD.  239 

found  in  deposits  older  than  the  Secondary,  in  any  region 
except  India ;  and  they  are  therefore  to  be  regarded  as  essen- 
tially Mesozoic  fossils.  Within  these  limits,  each  formation 
is  characterised  by  particular  species,  the  number  of  individ- 
uals being  often  very  great,  and  the  size  which  is  sometimes 
attained  being  nothing  short  of  gigantic.  In  the  Lias,  par- 
ticular species  of  Ammonites  may  succeed  one  another  regu- 
larly, each  having  a  more  or  less  definite  horizon,  which  it  does 
not  transgress.  It  is  thus  possible  to  distinguish  a  certain 
number  of  zones,  each  characterised  by  a  particular  Ammonite, 
together  with  other  associated  fossils.  Some  of  these  zones 
are  very  persistent  and  extend  over  very  wide  areas,  thus  afford- 
ing valuable  aid  to  the  geologist  in  his  determination  of 
rocks.  It  is  to  be  remembered,  however,  that  there  are  other 
species  which  are  not  thus  restricted  in  their  vertical  range, 
even  in  the  same  formations  in  which  definite  zones  occur. 

The  Cuttle-fishes  or  Dibranchiate  Cephalopods  constitute  a 
feature  in  the  life  of  the  Jurassic  period  little  less  conspicuous 
and  striking  than  that  afforded  by  the  multitudinous  and  varied 
chambered  shells  of  the  Ammonitida.  The  remains  by  which 
these  animals  are  recognised  are  necessarily  less  perfect,  as  a 
rule,  than  those  of  the  latter,  as  no  external  shell  is  present 
(except  in  rare  and  more  modern  groups),  and  the  internal 
skeleton  is  not  necessarily  calcareous.  Nevertheless,  we  have 
.  an  ample  record  of  the  Cuttle-fishes  of  the  Jurassic  period,  in 
the  shape  of  the  fossilised  jaws  or  beak,  the  ink-bag,  and,  most 
commonly  of  all,  the  horny  or  calcareous  structure  which  is 
embedded  in  the  soft  tissues,  and  is  variously  known  as  the 
"pen"  or  "bone."  The  beaks  of  Cuttle-fishes,  though  not 
abundant,  are  sufficiently  plentiful  to  have  earned  for  them- 
selves the  general  title  of  "  Rhyncholites  ; "  and  in  their  form 
and  function  they  resemble  the  horny,  parrot-like  beak  of  the 
existing  Cephalopods.  The  ink-bag  or  leathery  sac  in  which 
the  Cuttle-fishes  store  up  the  black  pigment  with  which  they 
obscure  the  water  when  attacked,  owes  its  preservation  to  the 
fact  that  the  colouring-matter  which  it  contains  is  finely-divid- 
ed carbon,  and  therefore  nearly  indestructible  except  by  heat. 
Many  of  these  ink-bags  have  been  found  in  the  Lias;  and  the 
colouring-matter  is  sometimes  so  well  preserved  that  it  has 
been,  as  an  experiment,  employed  in  painting  as  a  fossil 
"  sepia."  The  "  pens  "  of  the  Cuttle-fishes  are  not  commonly 
preserved,  owing  to  their  horny  consistence,  but  they  are  not 
unknown.  The  form  here  figured  (Beloteuthis  subcostata,  fig. 
172)  belonged  to  an  old  type  essentially  similar  to  our  modern 
Calamaries,  the  skeleton  of  which  consists  of  a  horny  shaft 


240 


HISTORICAL   PALAEONTOLOGY. 


Fig.  172.— Beloten- 
this  snbcostata.  J  ur- 
assic  (Lias). 


and  two  lateral  wings,  somewhat  like  a  feather  in  general 
shape.  When,  on  the  other  hand,  the  internal  skeleton  is 
calcareous,  then  it  is  very  easily  preserved 
in  a  fossil  condition  ;  and  the  abundance 
of  remains  of  this  nature  in  the  Secondary 
rocks,  combined  with  their  apparent  total 
absence  in  Palaeozoic  strata,  is  a  strong  pre- 
sumption in  favour  of  the  view  that  the  order 
of  the  Cuttle-fishes  did  not  come  into  exis- 
tence till  the  commencement  of  the  Meso- 
zoic" period.  The  great  majority  of  the  skele- 
tons of  this  kind  which  are  found  in  the  Jur- 
assic rocks  belong  to  the  great  extinct  family 
of  the  "  Belemnites  "  (Bdemnitidce\  which,  so 
far  as  known,  is  entirely  confined  to  rocks 
of  Secondary  age.  From  its  pointed,  gener- 
ally cylindro- conical  form,  the  skeleton  of 
the  Belemnitc  is  popularly  known  as  a  "thun- 
derbolt "  (fig.  173,  C).  In  its  perfect  condition 
— in  which  it  is,  however,  rarely  obtainable — 
the  skeleton  consists  of  a  chambered  conical 
shell  (the  "phragmacone  "),  the  partitions  between  the  chambers 
of  which  are  pierced  by  a  marginal  tube  or  "  siphuncle."  This 
conical  shell — curiously  similar  in  its  structure  to  the  external 
shell  of  the  Nautilus — is  extended  forwards  into  a  ^horny , 
"pen/'  and  is  sunk  in  a  corresponding  conical  pit  (fig.  173,  B), 
excavated  in  the  substance  of  a  nearly  cylindrical  fibrous 
body  or  "guard,'"'  which  projects  backwards  for  a  longer  or 
shorter  distance,  and  is  the  part  most  usually  found  in  a  fossil 
condition.  Many  different  kinds  of  Belemnites  are  known,  and 
their  guards  literally  swarm  in  many  parts  of  the  Jurassic  series, 
whilst  some  specimens  attain  very  considerable  dimensions. 
Not  only  is  the  internal  skeleton  known,  but  specimens  of 
Belemnites  and  the  nearly  allied  Belemnoteuthis  have  been  found 
in  some  of  the  fine-grained  sediments  of  the  Jurassic  formation, 
from  which  much  has  been  learnt  even  as  to  the  anatomy  of 
the  soft  parts  of  the  animal.  Thus  we  know  that  the  Belem- 
nites were  in  many  respects  comparable  with  the  existing 
Calamaries  or  Squids,  the  body  being  furnished  with  lateral 
fins,  and  the  head  carrying  a  circle  of  ten  "  arms/'  two  of 
which  were  longer  than  the  others  (fig.  173,  A).  The  suckers 
on  the  arms  were  provided,  further,  with  horny  hooks ;  there 
was  a  large  ink-sac ;  and  the  mouth  was  armed  with  horny 
mandibles  resembling  in  shape  the  beak  of  a  parrot. 

Coming  next  to  the  Vertebrates,  we  find  that  the  Jurassic 


THE  JURASSIC   PERIOD. 


24I 


Fishes  are  still  represented  by  Ganoids  and  Placoids.     The 
Ganoids,  however,  unlike  the  old  forms,  now  for  the  most 


A 


Fig.  173. — A,  Restoration  of  the  animal  of  the  Belemnite  ;  B,  Diagram  showing  the 
complete  skeleton  of  a  Belemnite,  consisting  of  the  chambered  phragmacone  (a),  the 
guard  (b),  and  the  horny  pen  (c)  ;  C,  Specimen  of  Belemnites  canaliculatus,  from  the 
Inferior  Oolite.  (After  Phillips.) 

part  possess  nearly  or  quite  symmetrical^"  homocercal")  tails. 
A  characteristic  genus  is   Tetragonolepis  (fig.    174),   with  its 


IV 

V 


1 


1 


Fig.  174.  —  Tetragonolepis  (restored),  and  scales  of  the  same.     Lias. 

deep,  compressed  body,  its  rhomboidal,  closely-fitting  scales, 
and  its  single  long  dorsal  fin.     Amongst  the  Placoids  the  teeth 


242 


HISTORICAL    PALAEONTOLOGY. 


Fig.  175.—  Tooth  of  'Acraittts  nobilis.     Lias. 


of  true  Sharks  (Notiddnus)  occur  for  the  first  time ;  but  by  far 
the  greater  number  of  remains  referable  to  this  group  are  still 
the  fin-spines  and  teeth  of  "  Cestracionts,"  resembling  the 
living  Port-Jackson  Shark.  Some  of  these  teeth  are  pointed 
(Hybodus] ;  but  others  are  rounded,  and  are  adapted  for  crush- 
ing shell-fish.  Of  these  latter,  the  commonest  are  the  teeth  of 
Acrodus  (fig.  175),  of  which  the  hinder  ones  are  of  an  elon- 
gated form,  with  a  rounded 
surface,  covered  with  fine 
transverse  striae  proceed- 
ing from  a  central  longi- 
tudinal line.  From  their 
general  form  and  striation, 
and  their  dark  colour,  these 
teeth  are  commonly  called 
"fossil  leeches"  by  the  quarrymen. 

The  Amphibian  group  of  the  Labyrinthodonts,  which  was  so 
extensively  developed  in  the  Trias,  appears  to  have  become 
extinct,  no  representative  of  the  order  having  hitherto  been 
detected  in  rocks  of  Jurassic  age. 

Much  more  important  than  the  Fishes  of  the  Jurassic  series 
are  the  Reptiles,  which  are  both  very  numerous,  and  belong  to 
a  great  variety  of  types,  some  of  these  being  very  extraordinary 
in  their  anatomical  structure.  The  predominant  group  is  that 
of  the  "  Enaliosaurs  "  or  "  Sea-lizards,"  divided  into  two  great 
orders,  represented  respectively  by  the  Ichthyosaurus  and  the 
Plesiosaurus. 

The  Ichthyosauri  or  "  Fish- Lizards  "  are  exclusively  Meso- 
zoic  in  their  distribution,  ranging  from  the  Lias  to  the  Chalk, 
but  abounding  especially  in  the  former.  They  were  huge 
Reptiles,  of  a  fish-like  form,  with  a  hardly  conspicuous  neck 
(fig.  176),"  and  probably  possessing  a  simply  smooth  or 


— Ichthyosaurus  contmunis.     Lias. 


wrinkled  skin,  since  no  traces  of  scales  or  bony  integumentary 
plates  have  ever  been  discovered.  The  tail  was  long,  and 
was  probably  furnished  at  its  extremity  with  a  powerful  ex- 
pansion of  the  skin,  constituting  a  tail-fin  similar  to  that  pos- 
sessed bv  the  Whales.  The  limbs  are  also  like  those  of  Whales 


THE  JURASSIC   PERIOD.  243 

in  the  essentials  of  their  structure,  and  in  their  being  adapted 
to  act  as  swimming-paddles.  Unlike  the  Whales,  however, 
the  Ichthyosaurs  possessed  the  hind-limbs  as  well  as  the  fore- 
limbs,  both  pairs  having  the  bones  flattened  out  and  the  fin- 
gers completely  enclosed  in  the  skin,  the  arm  and  leg  being  at 
the  same  time  greatly  shortened.  The  limbs  are  thus  con- 
verted into  efficient  "  flippers,"  adapting  the  animal  for  an 
active  existence  in  the  sea.  The  different  joints  of  the  back- 
bone (vertebrae)  also  show  the  same  adaptation  to  an  aquatic 
mode  of  life,  being  hollowed  out  at  both  ends,  like  the  bicon- 
cave vertebrae  of  Fishes.  The  spinal  column  in  this  way  was 
endowed  with  the  flexibility  necessary  for  an  animal  intended 
to  pass  the  greater  part  of  its  time  in  water.  Though  the  Ich- 
thyosaurs are  undoubtedly  marine  animals,  there  is,  however, 
reason  to  believe  that  they  occasionally  came  on  shore,  as  they 
possess  a  strong  bony  arch,  supporting  the  fore-limbs,  such  as 
would  permit  of  partial,  if  laborious,  terrestrial  progression. 
The  head  is  of  enormous  size,  with  greatly  prolonged  jaws, 
holding  numerous  powerful  conical  teeth  lodged  in  a  common 
groove.  The  nature  of  the  dentil  apparatus  is  such  as  to 
leave  no  doubt  as  to  the  rapacious  and  predatory  habits  of  the 
Ichthyosaurs — an  inference  which  is  further  borne  out  by  the 
examination  of  their  petrified  droppings,  which  are  known  to 
geologists  as  "  coprolites,"  and  which  contain  numerous  frag- 
ments of  the  bones  and  scales  of  the  Ganoid  fishes  which 
inhabited  the  same  seas.  The  orbits  are  of  huge  size ;  and  as 
the  eyeball  was  protected,  like  that  of  birds,  by  a  ring  of  bony 
plates  in  its  outer  coat,  we  even  know  that  the  pupils  of  the 
eyes  were  of  correspondingly  large  dimensions.  As  these  bony 
plates  have  the  function  of  protecting  the  eye  from  injury 
under  sudden  changes  of  pressure  in  the  surrounding  medium, 
it  has  been  inferred,  with  great  probability,  that  the  Ichthy- 
csaurs  were  in  the  habit  of  diving  to  considerable  depths  in 
the  sea.  Some  of  the  larger  specimens  of  Ichthyosaurus  which 
have  been  discovered  in  the  Lias  indicate  an  animal  of  from 
20  to  nearly  40  feet  in  length  ;  and  many  species  are  known  to 
have  existed,  whilst  fragmentary  remains  of  their  skeletons  are 
very  abundant  in  some  localities.  We  may  therefore  safely 
conclude  that  these  colossal  Reptiles  were  amongst  the  most 
formidable  of  the  many  tyrants  of  the  Jurassic  seas. 

The  PUsiosaurus  (fig.  177)  is  another  famous  Oolitic 
Reptile,  and,  like  the  preceding,  must  have  lived  mainly  or 
exclusively  in  the  sea.  It  agrees  with  the  Ichthyosaur  in  some 
important  features  of  its  organisation,  especially  in  the  fact 
tliat  both  pairs  of  limbs  are.  converted  into  "flippers"  or 


244  HISTORICAL   PALEONTOLOGY. 

swimming-paddles,  whilst  the  skin  seems  to  have  been  equally 
destitute  of  any  scaly  or  bony  investiture.     Unlike  the  Ichthy- 


Fig.  177. — Plesiosaurus  dolichodeims,  restored.     Lias. 

osaur,  however,  the  Plesiosaur  had  the  paddles  placed  far  back, 
the  tail  being  extremely  short,  and  the  neck  greatly  lengthened 
out,  and  composed  of  from  twenty  to  forty  vertebrae.  The 
bodies  of  the  vertebrae,  also,  are  not  deeply  biconcave,  but  are 
flat,  or  only  slightly  cupped.  The  head  is  of  relatively  small 
size,  with  smaller  orbits  than  those  of  the  Ichthyosaur,  and  with 
a  snout  less  elongated.  The  jaws,  however,  were  armed  with 
numerous  conical  teeth,  inserted  in  distinct  sockets.  As  re- 
gards the  habits  of  the  Plesiosaur,  Dr  Conybeare  arrives  at  the 
following  conclusions  :  "  That  it  was  aquatic  is  evident  from 
the  form  of  its  paddles  ;  that  it  was  marine  is  almost  equally 
so  from  the  remains  with  which  it  is  universally  associated ; 
that  it  may  have  occasionally  visited  the  shore,  the  resem- 
blance of  its  extremities  to  those  of  the  Turtles  may  lead  us  to 
conjecture :  its  movements,  however,  must  have  been  very- 
awkward  on  land ;  and  its  long  neck  must  have  impeded  its 
progress  through  the  water,  presenting  a  strong  contrast  to  the 
organisation  which  so  admirably  fits  the  Ichthyosaurus  to  cut 
through  the  waves."  As  its  respiratory  organs  were  such  that 
it  must  of  necessity  have  required  to  obtain  air  frequently,  we 
may  conclude  "  that  it  swam  upon  or  near  the  surface,  arching 
back  its  long  neck  like  a  swan,  and  occasionally  darting  it 
down  at  the  fish  which  happened  to  float  within  its  reach.  It 
may  perhaps  have  lurked  in  shoal  water  along  the  coast,  con- 
cealed amongst  the  sea  -  weed  ;  and  raising  its  nostrils  to  a 


THE   JURASSIC    PERIOD.  245 

level  with  the  surface  from  a  considerable  depth,  may  have 
found  a  secure  retreat  from  the  assaults  of  powerful  enemies ; 
while  the  length  and  flexibility  of  its  neck  may  have  compen- 
sated for  the  want  of  strength  in  its  jaws,  and  its  incapacity 
for  swift  motion  through  the  water." 

About  twenty  species  of  Plesiosaums  are  known,  ranging 
from  the  Lias  to  the  Chalk,  and  specimens  have  been  found 
indicating  a  length  of  from  eighteen  to  twenty  feet.  The 
nearly  related  " Pliosaurs"  however,  with  their  huge  heads 
and  short  necks,  must  have  occasionally  reached  a  length  of  at 
least  forty  feet — the  skull  in  some  species  being  eight,  and  the 
paddles  six  or  seven  feet  long,  whilst  the  teeth  are  a  foot  in 
length. 

Another  extraordinary  group  of  Jurassic  Reptiles  is  that  of 
the  "  Winged  Lizards  "  or  Pterosaur ia.  These  are  often  spoken 
of  collectively  as  "  Pterodactyles,"  from  Pterodadylus,  the 
type-genus  of  the  group.  As  now  restricted,  however,  the 
genus  Pierodactylus  is  more  Cretaceous  than  Jurassic,  and  it  is 
associated  in  the  Oolitic  rocks  with  the  closely  allied  genera 
Dimorphodon  and  Rhamphorhynchus.  In  all  three  of  these 
genera  we  have  the  same  general  structural  organisation,  in- 
volving a  marvellous  combination  of  characters,  which  we  are  in 
the  habit  of  regarding  as  peculiar  to  Birds  on  the  one  hand,  to 
Reptiles  on  another  hand,  and  to  the  Flying  Mammals  or 
Bats  in  a  third  direction.  The  "  Pterosaurs  "  are  "  Flying  " 
Reptiles,  in  the  true  sense  of  the  term,  since  they  were  indu- 
bitably possessed  of  the  power  of  active  locomotion  in  the  air, 
after  the  manner  of  Birds.  The  so-called  "  Flying  "  Reptiles 
of  the  present  day,  such  as  the  little  Draco  volans  of  the  East 
Indies  and  Indian  Archipelago,  possess,  on  the  other  hand,  no 
power  of  genuine  flight,  being  merely  able  to  sustain  themselves 
in  the  air  through  the  extensive  leaps  which  they  take  from  tree 
to  tree,  the  wing-like  expansions  of  the  skin  simply  exercising 
the  mechanical  function  of  a  parachute.  The  apparatus  of  flight 
in  the  "Pterosaurs"  is  of  the  most  remarkable  character,  and 
most  resembles  the  "wing"  of  a  Bat,  though  very  different  in 
some  important  particulars.  The  "wing"  of  the  Pterosaurs  is 
like  that  of  Bats,  namely,  in  consisting  of  a  thin  leathery  expan- 
sion of  the  skin  which  is  attached  to  the  sides  of  the  body,  and 
stretches  between  the  fore  and  hind  limbs,  being  mainly  sup- 
ported by  an  enormous  elongation  of  certain  of  the  digits  of 
the  hand.  In  the  Bats,  it  is  the  four  outer  fingers  which  are 
thus  lengthened  out ;  but  in  the  Pterosaurs,  the  wing-membrane 
is  borne  by  a,  single  immensely -extended  finger  (fig.  178). 
.No  trace  of  the  actual  wing-membrane  itself  has,  of  course, 


246  HISTORICAL   PALEONTOLOGY. 

been  found  fossilised  ;  but  we  could  determine  that  the  "  Ptero- 
dactyles  ".possessed  the  power  of  flight,  quite  apart  from  the  ex- 


Fig.  178. — Pterodactylus  crassirostris.  From  the  Lithographic  Slates  of  Solenhofen 
(Middle  Oolite).  The  figure  is  "  restored,"  and  it  seems  certain  that  the  restoration  is 
incorrect  in  the  comparatively  unimportant  particular,  that  the  hand  should  consist  of  no 
more  than  four  fingers,  three  short  and  one  long,  instead  of  five,  as  represented. 

traordinary  conformation  of  the  hand.  The  proofs  of  this  are  to 
be  found  partly  in  the  fact  that  the  breast-bone  was  furnished 
with  an  elevated  ridge  or  keel,  serving  for  the  attachment  of 
the  great  muscles  of  flight,  and  still  more  in  the  fact  that  the' 
bones  were  hollow  and  were  filled  with  air  —  a  peculiarity 
wholly  confined  amongst  living  animals  to  Birds  only.  The 
skull  of  the  Pterosaurs  is  long,  light,  and  singularly  bird-like  in 
appearance — a  resemblance  which  is  further  increased  by  the 
comparative  length  of  the  neck  and  the  size  of  the  vertebrae  of 
this  region  (fig.  178).  The  jaws,  however,  unlike  those  of  any 
existing  Bird,  were,  with  one  exception  to  be  noticed  hereafter, 
furnished  with  conical  teeth  sunk  in  distinct  sockets ;  and 
there  was  always  a  longer  or  shorter  tail  composed  of  distinct 
vertebras ;  whereas  in  all  existing  Birds  the  tail  is  abbreviated, 
and  the  terminal  vertebrae  are  amalgamated  to  form  a  single 
bone,  which  generally  supports  the  great  feathers  of  the  tail. 

Modern  naturalists  have  been  pretty  generally  agreed  that 
the  Pterosaurs  should  be  regarded  as  a  peculiar  group  of  the 
Reptiles  ;  though  they  have  been  and  are  still  regarded  by 
high  authorities,  like  Professor  Seeley,  as  being  really  referable 


THE  JURASSIC    PERIOD.  247 

to  the  Birds,  or  as  forming  a  class  by  themselves.  The  chief 
points  which  separate  them  from  Birds,  as  a  class,  are  the 
character  of  the  apparatus  of  flight,  the  entirely  different  struc- 
ture of  the  fore-limb,  the  absence  of  feathers,  the  composition 
of  the  tail  out  of  distinct  vertebrae,  and  the  general  presence 
of  conical  teeth  sunk  in  distinct  sockets  in  the  jaws.  The  gap 
between  the  Pterosaurs  and  the  Birds  has,  however,  been 
greatly  lessened  of  late  by  the  discovery  of  fossil  animals 
\Ichthyornis  and  Hesperornis]  with  the  skeleton  proper  to  Birds 
combined  with  the  presence  of  teeth  in  the  jaws,  and  by  the 
still  more  recent  discovery  of  other  fossil  animals  (Ptcranodon) 
with  a  Pterosaurian  skeleton,  but  without  teeth;  whilst  the  un- 
doubtedly feathered  Arch&opteryx  possessed  a  long  tail  com- 
posed of  separate  vertebrae.  Upon  the  whole,  therefore,  the 
relationships  of  the  Pterosaurs  cannot  be  regarded  as  absolutely 
settled.  It  seems  certain,  however,  that  they  did  not  possess 
feathers — this  implying  that  they  were  cold-blooded  animals  ; 
and  their  affinities  with  Reptiles  in  this,  as  in  other  characters, 
are  too  strong  to  be  overlooked. 

The  Pterosaurs  are  wholly  Mesozoic,  ranging  from  the  Lias 
to  the  Chalk  inclusive  ;  and  the  fine-grained  Lithographic  Slate 
of  Solenhofen  has  proved  to  be  singularly  rich  in  their  remains. 
The  genus  Pterodactylus  itself  has  the  jaws  toothed  to  the  ex- 
tremities with  equal-sized  conical  teeth,  and  its  species  range 
from  the  Middle  Oolites  to  the  Cretaceous  series,  in  connec- 
tion with,  which  they  will  be  again  noticed,  together  with  the 
toothless  genus  Pterauodon.  The  genus  Dimorphodon  is  Li- 
assic,  and  is  characterised  by  having  the  front  teeth  long  and 
pointed,  whilst  the  hinder  teeth  are  small  and  lancet-shaped. 
Lastly,  the  singular  genus  Rhamphgrhynckus^  also  from  the 
Lower  Oolites,  is  distinguished  by  the  fact  that  there  are  teeth 
present  in  the  hinder  portions  of  both  jaws;  but  the  front  por- 
tions are  toothless,  and  may  have  constituted  a  horny  beak. 
Like  most  of  the  other  Jurassic  Pterosaurs,  Rhamphorhytuh&s 
(fig.  179)  does  not  seem  to  have  been  much  bigger  than  a 
pigeon,  in  this  respect  felling  for  below  the  giant  "Dragons" 
of  the  Cretaceous  period.  It  differed  from  its  relatives,  not 
only  in  the  armature  of  the  mouth,  but  also  in  the  fact  that 
the  tail  was  of  considerable  length.  With  regard  to  its  habits 
and  mode  of  life,  Professor  Phillips  remarks  that,  "gifted  with 
ample  means  of  flight,  able  at  least  to  perch  on  rocks  and 
scuffle  along  the  shore,  perhaps  competent  to  dive,  though  not 
so  well  as  a  Palmiped  bird,  many  fishes  must  have  yielded  to 
the  cruel  beak  and  sharp  teeth  of  Rhamphorhynchus.  If  we 
ask  to  which  of  the  many  families  of  Birds  the  analogy  of 


248  HISTORICAL   PALEONTOLOGY. 

structure  and  probable  way  of  life  would  lead  us  to  assimilate 
Rhamphorhynchus,  the  answer  must  point  to  the  swimming 


Fig.  179. — Rhamphorhynchns  Bitcklandi,  restored.     Bath  Oolite,  England. 
(After  the  late  Professor  Phillips.) 

races  with  long  wings,  clawed  feet,  hooked  beak,  and  habits  of 
violence  and  voracity  ;  and  for  preference,  the  shortness  of  the 
legs,  and  other  circumstances,  may  be  held  to  claim  for  the 
Stonesfield  fossil  a  more  than  fanciful  similitude  to  the  groups 
of  Cormorants,  and  other  marine  divers,  which  constitute  an 
effective  part  of  the  picturesque  army  of  robbers  of  the  sea." 

Another  extraordinary  and  interesting  group  of  the  Mesozoic 
Reptiles  is  constituted  by  the  Deinosauria,  comprising  a  series 
of  mostly  gigantic  forms,  which  range  from  the  Trias  to  the 
Chalk.  All  the  "  Deinosaurs  "  are  possessed  of  the  two  pairs 
of  limbs  proper  to  Vertebrate  animals,  and  these  organs  are  in 
the  main  adapted  for  walking  on  the  dry  land.  Thus,  whilst 
the  Mesozoic  seas  swarmed  with  the  huge  Ichthyosaurs  and 
Plesiosaurs,  and  whilst  the  air  was  tenanted  by  the  Dragon-like 
Pterosaurs,  the  land  -  surfaces  of  the  Secondary  period  were 
peopled  by  numerous  forms  of  Deinosaurs,  some  of  them  of 
even  more  gigantic  dimensions  than  their  marine  brethren. 
The  limbs  of  the  Deinosaurs  are,  as  just  said,  adapted  for  pro- 
gression on  the  land  ;  but  in  some  cases,  at  any  rate,  the 
hind-limbs  were  much  longer  and  stronger  than  the  fore-limbs ; 
and  there  seems  to  be  no  reason  to  doubt  that  many  of  these 
forms  possessed  the  power  of  walking,  temporarily  or  perman- 
ently, on  their  hind-legs,  thus  presenting  a  singular  resemblance 
to  Birds.  Some  very  curious  and  striking  points  connected 
with  the  structure  of  the  skeleton  have  also  been  shown  to 
connect  these  strange  Reptiles  with  the  true  Birds ;  and  such 
high  authorities  as  Professors  Huxley  and  Cope  are  of  opinion 
that  the  Deinosaurs  are  distinctly  related  to  this  class,  being  in 
some  respects  intermediate  between  the  proper  Reptiles  and 
the  great  wingless  Birds,  like  the  Ostrich  and  Cassowary.  On 
the  other  hand,  Professor  Owen  has  shown  that  the  Deinosaurs 


THE   JURASSIC   PERIOD. 


249 


possess  some  weighty  points  of  relationship  with  the  so-called 
"Pachydermatous"  Quadrupeds,  such  as  the  Rhinoceros  and 
Hippopotamus.  The  most  important  Jurassic  genera  of 
Deinosauria  are  Megalysaurus  and  Cetiosaurus,  both  of  which 
extend  their  range  into  the  Cretaceous  period,  in  which 
flourished,  as  we  shall  see,  some  other  well-known  members 
of  this  order. 

Megalosaurus  attained  gigantic  dimensions,  its  thigh  and 
shank  bones  measuring  each  about  three  feet  in  length,  and  its 
total  length,  including  the  tail,  being  estimated  at  from  forty 
to  fifty  feet.  As  the  head  of  the  thigh-bone  is  set  on  nearly 
at  right  angles  with  the  shaft,  whilst  all  the  long  bones  of  the 
skeleton  are  hollowed  out  internally  for  the  reception  of  the 
marrow,  there  can  be  no  doubt  as  to  the  terrestrial  habits  of 
the  animal.  The  skull  (fig.  180)  was  of  large  size,  four  or  five 


Fig.  180. — Skull  of  Megalostiurus,  on  a  scale  one-tenth  of  nature. 
(After  Professor  Phillips.) 


Restored. 


feet  in  length,  and  the  jaws  were  armed  with  a  series  of  power- 
ful pointed  teeth.  The  teeth  are  conical  in  shape,  but  are 
strongly  compressed  towards  their  summits,  their  lateral  edges 
being  finely  serrated.  In  their  form  and  their  saw-like  edges, 
they  resemble  the  teeth  of  the  "  Sabre-toothed  Tiger"  (Machai- 
rodus\  and  they  render  it  certain  that  the  Megalosaur  was  in 
the  highest  degree  destructive  and  carnivorous  in  its  habits. 
So  far  as  is  known,  the  skin  was  not  furnished  with  any  armour 
of  scales  or  bony  plates ;  and  the  fore-limbs  are  so  dispro- 
portionately small  as  compared  with  the  hind-limbs,  that  this 
huge  Reptile — like  the  equally  huge  Iguanodon  —  may  be 


250  HISTORICAL   PALEONTOLOGY. 

conjectured  to  have  commonly  supported  itself  on  its  hind- 
legs  only. 

The  Cetiosaur  attained  dimensions  even  greater  than  those 
of  the  Megalosaur,  one  of  the  largest  thigh-bones  measuring 
over  five  feet  in  length  and  a  foot  in  diameter  in  the  middle, 
and  the  total  length  of  the  animal  being  probably  not  less  than 
fifty  feet.  It  was  originally  regarded  as  a  gigantic  Crocodile, 
but  it  has  been  shown  to  be  a  true  Deinosaur.  Having  ob- 
tained a  magnificent  series  of  remains  of  this  reptile,  Professor 
Phillips  has  been  able  to  determine  many  very  interesting 
points  as  to  the  anatomy  and  habits  of  this  colossal  animal,- 
the  total  length  of  which  he  estimates  as  being  probably  not 
less  than  sixty  or  seventy  feet.  As  to  its  mode  of  life,  this 
accomplished  writer  remarks  : — 

"  Probably  when  '  standing  at  ease '  not  less  than  ten  feet 
in  height,  and  of  a  bulk  in  proportion,  this  creature  was  un- 
matched in  magnitude  and  physical  strength  by  any  of  the 
largest  inhabitants  of  the  Mesozoic  land  or  sea.  Did  it  live 
in  the  sea,  in  fresh  waters,  or  on  the  land  ?  This  question 
cannot  be  answered,  as  in  the  case  of  Ichthyosaurus,  by  appeal 
to  the  accompanying  organic  remains;  for  some  of  the  bones 
lie  in  marine  deposits,  others  in  situations  marked  by  estuarine 
conditions,  and,  out  of  the  Oxfordshire  district,  in  Sussex,  in 
fiuviatile  accumulations.  Was  it  fitted  to  live  exclusively  in 
water?  Such  an  idea  was  at  one  time  entertained,  in  conse- 
quence of  the  biconcave  character  of  the  caudal  vertebrae,  and 
it  is  often  suggested  by  the  mere  magnitude  of  the  creature, 
which  would  seem  to  have  an  easier  life  while  floating  in  water, 
than  when  painfully  lifting  its  huge  bulk,  and  moving  with 
slow  steps  along  the  ground.  But  neither  of  these  arguments 
is  valid.  The  ancient  earth  was  trodden  by  larger  quadrupeds 
than  our  elephant ;  and  the  biconcave  character  of  vertebrae, 
which  is  not  uniform  along  the  column  in  Cetiosaurus,  is  per- 
haps as  much  a  character  of  a  geological  period  as  of  a  me- 
chanical function  of  life.  Good  evidence  of  continual  life  in 
water  is  yielded  in  the  case  of  Ichthyosaurus  and  other  Ena- 
liosaurs,  by  the  articulating  surfaces  of  their  limb-bones,  for 
these,  all  of  them,  to  the  last  phalanx,  have  that  slight  and 
indefinite  adjustment  of  the  bones,  with  much  intervening 
cartilage,  which  fits  the  leg  to  be  both  a  flexible  and  forcible 
instrument  of  natation,  much  superior  to  the  ordinary  oar- 
blade  of  the  boatman.  On  the  contrary,  in  Cetiosaur,  as  well 
as  in  Megalosaur  and  Iguanodon,  all  the  articulations  are 
definite,  and  made  so  as  to  correspond  to  determinate  move- 
ments in  particular  directions,  and  these  are  such  as  to  be 


THE  JURASSIC   PERIOD.  251 

suited  for  walking.  In  particular,  the  femur,  by  its  head  pro- 
jecting freely  from  the  acetabulum,  seems  to  claim  a  movement 
of  free  stepping  more  parallel  to  the  line  of  the  body,  and 
more  approaching  to  the  vertical  than  the  sprawling  gait  of 
the  crocodile.  The  large  claws  concur  in  this  indication  of 
terrestrial  habits.  But,  on  the  other  hand,  these  characters 
are  not  contrary  to  the  belief  that  the  animal  may  have  been 
amphibious ;  and  the  great  vertical  height  of  the  anterior  part 
of  the  tail  seems  to  support  this  explanation,  but  it  does  not 
go  further.  .  .  .  We  have  therefore  a  marsh-loving  or 
river-side  animal,  dwelling  amidst  filicine,  cycadaceous,  and 
coniferous  shrubs  and  trees  full  of  insects  and  small  mamma- 
lia. What  was  its  usual  diet  ?  If  ex  ungue  leonem,  surely  ex 
dente  cibum.  We  have  indeed  but  one  tooth,  and  that  small 
and  incomplete.  It  resembles  more  the  tooth  of  Iguanodon 
than  that  of  any  other  reptile ;  for  this  reason  it  seems  pro- 
bable that  the  animal  was  nourished  by  similar  vegetable  food 
which  abounded  in  the  vicinity,  and  was  not  obliged  to  con- 
tend with  Megalosaurus  for  a  scanty  supply  of  more  stimu- 
lating diet." 

All  the  groups  of  Jurassic  Reptiles  which  we  have  hitherto 
been  considering  are  wholly  unrepresented  at  the  present  day, 
and  do  not  even  pass  upwards  into  the  Tertiary  period.  It 
may  be  mentioned,  however,  that  the  Oolitic  deposits  have 
also  yielded  the  remains  of  Reptiles  belonging  to  three  of  the 
existing  orders  of  the  class — namely,  the  Lizards  ( Later tilia), 
the  Turtles  (Chdonia),  and  the  Crocodiles  (Crocodilia).  The 
Lizards  occur  both  in  the  marine  strata  of  the  Middle  Oolites 
and  also  in  the  fresh-water  beds  of  the  Purbeck  series ;  and 
they  are  of  such  a  nature  that  their  affinities  with  the  typical 
Lacertilians  of  the  present  day  cannot  be  disputed.  The 
Chelonians,  up  to  this  point  only  known  by  the  doubtful  evi- 
dence of  footprints  in  the  Permian  and  Triassic  sandstones,  are 
here  represented  by  unquestionable  remains,  indicating  the  ex- 
istence of  marine  Turtles  (the  Chehne planiceps  of  the  Portland 
Stone).  No  remains  of  Serpents  ( Ophidians]  have  as  yet  been 
detected  in  the  Jurassic ;  but  strata  of  this  age  have  yielded 
the  remains  of  numerous  Crocodilians,  which  probably  inhab- 
ited the  sea.  The  most  important  member  of  this  group'is 
Teleosaiirus,  which  attained  a  length  of  over  thirty  feet,  and 
is  in  some  respects  allied  to  the  living  Gavials  of  India. 

The  great  class  of  the  Birds,  as  we  have  seen,  is  represented 
in  rocks  earlier  than  the  Oolites  simply  by  the  not  absolutely 
certain  evidence  of  the  three-toed  footprints  of  the  Connecti- 
cut Trias.  In  the  Lithographic  Slate  of  Solenhofen  (Middle 


252 


HISTORICAL   PALAEONTOLOGY. 


Oolite),  there  has  been  discovered,  however,  the  at  present 
unique  skeleton  of  a  Bird  well  known  under  the  name  of  the 
Archceopteryx  macrura  (figs.  181,  182).  The  only  known 


Fig.  181.—  ArcJueopteryx  macrnra,  showing  tail  and  tail-feathers,  with  detached  bones. 
Reduced.     From  the  Lithographic  Slate  of  Solenhofen. 

specimen— now  in  the  British  Museum — unfortunately  does 
not  exhibit  the  skull;    but  the  fine-grained  matrix  has  pre- 


Fig.  182. — Restoration  of  A  rchceopteryx  macrio-a.     (After  Owen.) 

served  a  number  of  the  other  bones  of  the  skeleton,  along  with 
the  impressions  of  the  tail  and  wing  feathers.  From  these 
remains  we  know  that  Archceopteryx  differed  in  some  remark- 


THE  JURASSIC   PERIOD.  253 

able  peculiarities  of  its  structure  from  all  existing  members  of 
the  class  of  Birds.  This  extraordinary  Bird  (fig.  182)  appears 
to  have  been  about  as  big  as  a  Rook — the  tail  being  long  and 
extremely  slender,  and  composed  of  separate  vertebrae,  each 
of  which  supports  a  single  pair  of  quill-feathers.  In  the  flying 
Birds  of  the  present  day,  as  before  mentioned,  the  terminal 
vertebrae  of  the  tail  are  amalgamated  to  form  a  single  bone 
("  ploughshare-bone  "),  which  supports  a  cluster  of  tail-feathers  ; 
and  the  tail  itself  is  short.  In  the  embryos  of  existing  Birds 
the  tail  is  long,  and  is  made  up  of  separate  vertebrae,  and  the 
same  character  is  observed  in  many  existing  Reptiles.  The 
tail  of  Arch&opteryx\  therefore,  is  to  be  regarded  as  the  per- 
manent retention  of  an  embryonic  type  of  structure,  or  as  an 
approximation  to  the  characters  of  the  Reptiles.  Another 
remarkable  point  in  connection  with  Arcfuzopteryx,  in  which 
it  differs  from  all  known  Birds,  is,  that  the  wing  was  furnished 
with  two  free  claws.  From  the  presence  of  feathers,  Archce- 
opteryx  may  be  inferred  to  have  been  hot-blooded ;  and  this 
character,  taken  along  with  the  structure  of  the  skeleton  of  the 
wing,  may  be  held  as  sufficient  to  justify  its  being  considered 
as  belonging  to  the  class  of  Birds.  In  the  structure  of  the 
tail,  however,  it  is  singularly  Reptilian ;  and  there  is  reason  to 
believe  that  its  jaws  were  furnished  with  teeth  sunk  in  distinct 
sockets,  as  is  the  case  in  no  existing  Bird.  This  conclusion, 
at  any  rate,  is  rendered  highly  probable  by  the  recent  discovery 
of  "Toothed  Birds"  (Odontornithes)  in  the  Cretaceous  rocks 
of  North  America. 

The  Mammals  of  the  Jurassic  period  are  known  to  us  by 
a  number  of  small  forms  which  occur  in  the  "  Stonesfield 
Slate"  (Great  Oolite)  and  in  the  Purbeck  beds  (Upper 
Oolite).  The  remains  of  these  are  almost  exclusively  sepa- 
rated halves  of  the  lower  jaw,  and  they  indicate  the  existence 
during  the  Oolitic  period  in  Europe  of  a  number  of  small 
"  Pouched  animals "  {Marsupials}.  In  the  horizon  of  the 
Stonesfield  Slate  four  genera  of  these  little  Quadrupeds  have 
been  described  —  viz.,  Amphilestes,  Amphitherium,  Phascolo- 
therium,  and  Stereognathus.  In  Amphitherium  (fig.  183),  the 
molar  teeth  are  furnished  with  small  pointed  eminences  or 
"  cusps ; "  and  the  animal  was  doubtless  insectivorous.  By 
Professor  Owen,  the  highest  living  authority  on  the  subject, 
Amphitherium  is  believed  to  be  a  small  Marsupial,  most 
nearly  allied  to  the  living  Banded  Ant-eater  (Myrmecobius)  of 
Australia  (fig.  158).  Amphilestes  and  Phascolotherium  (fig. 
184)  are  also  believed  by  the  same  distinguished  anatomist 
and  palaeontologist  to  have  been  insect-eating  Marsupials,  and 
13 


254 


HISTORICAL   PALAEONTOLOGY. 


the  latter  is  supposed  to  find  its  nearest  living  ally  in  the 
Opossums  (Didelphys)  of  America.     Lastly,  the  Stereognathiis 


Fig.  183. — Lower  jaw  of  A  •mphitherinm  (TJiylncotherimii)  Prevostii. 
Stonesfield  Slate  (Great  Oolite.) 

of  the  Stonesfield  Slate  is  in  a  dubious  position.  It  may  have 
been  a  Marsupial ;  but,  upon  the  whole,  Professor  Owen  is 
inclined  to  believe  that  it  must  have  been  a  hoofed  and  her- 
bivorous Quadruped  belonging  to  the  series  of  the  higher  Mam- 
mals (Placentalia).  In  the  Middle  Purbeck  beds,  near  to  the 
close  of  the  Oolitic  period,  we  have  also  evidence  of  the  exist- 
ence of  a  number  of  small  Mammals,  all  of  which  are  probably 
Marsupials.  Fourteen  species  are  known,  all  of  small  size, 
the  largest  being  no  bigger  than  a  Polecat  or  Hedgehog.  The 
genera  to  which  these  little  quadrupeds  have  been  referred  are 
Plagiaiilax,  Spalacotherium,  Triconodon,  and  Galestes.  The 
first  of  these  (fig.  184,  4)  is  believed  by  Professor  Owen  to 


Fig.  184.  Oolitic  Mammals. — i,  Lower  jaw  and  teeth  of  Phascolotherium,  Stonesfield 
Slate  ;  2,  Lower  jaw  and  teeth  of  Amphitherium,  Stonesfield  Slate  ;  3,  Lower  jaw  and 
teeth  of  Triconodon,  Purbeck  beds  ;  4,  Lower  jaw  and  teeth  of  Plagiatilax,  Purbeck 
beds.  All  the  figures  are  of  the  natural  size. 

have  been  carnivorous  in  its  habits ;  but  other  authorities 
maintain  that  it  was  most  nearly  allied  to  the  living  Kangaroo- 
rats  (Hypsiprymmts)  of  Australia,  and  that  it  was  essentially 
herbivorous.  The  remaining  three  genera  appear  to  have 
been  certainly  insectivorous,  and  find  their  nearest  living  rep- 
resentatives in  the  Australian  Phalangers  and  the  American 
Opossums. 

Finally,  it  is  interesting  to  notice  in  how  many  respects  the 


THE  JURASSIC   PERIOD.  255 

Jurassic  fauna  of  Western  Europe  approached  to  that  now 
inhabiting  Australia.  At  the  present  day,  Australia  is  almost 
wholly  tenanted  by  Marsupials ;  upon  its  land-surface  flourish 
Araucarice  and  Cycadaceous  plants,  and  in  its  seas  swims  the 
Port-Jackson  Shark  (Cestracion  Philippi) >;  whilst  the  Mollus- 
can  genus  Trigonia  is  nowadays  exclusively  confined  to  the 
Australian  coasts.  In  England,  at  the  time  of  the  deposition 
of  the  Jurassic  rocks,  we  must  have  had  a  fauna  and  flora  very 
closely  resembling  what  we  now  see  in  Australia.  The  small 
Marsupials,  Amphitheriiim,  Phascolotherium,  and  others,  prove 
that  the  Mammals  were  the  same  in  order;  cones  of  Arau- 
carian  pines,  with  tree-ferns  and  fronds  of  Cycads,  occur 
throughout  the  Oolitic  series;  spine-bearing  fishes,  like  the 
Port-Jackson  Shark,  are  abundantly  represented  by  genera 
such  as  Acrodus  and  Strophodus  ;  and  lastly,  the  genus  Tri- 
gonia^ now  exclusively  Australian,  is  represented  in  the  Oolites 
by  species  which  differ  little  from  those  now  existing.  More- 
over, the  discovery  during  recent  years  of  the  singular  Mud-fish, 
the  Ceratodus  Fosteri,  in  the  rivers  of  Queensland,  has  added 
another  and  a  very  striking  point  of  resemblance  to  those 
already  mentioned ;  since  this  genus  of  Fishes,  though  pre- 
eminently Triassic,  nevertheless  extended  its  range  into  the 
Jurassic.  Upon  the  whole,  therefore,  there  is  reason  to  con- 
clude that  Australia  has  undergone  since  the  close  of  the 
Jurassic  period  fewer  changes  and  vicissitudes  than  any  other 
known  region  of  the  globe ;  and  that  this  wonderful  continent 
has  therefore  succeeded  in  preserving  a  greater  number  of 
the  characteristic  life-features  of  the  Oolites  than  any  other 
country  with  which  we  are  acquainted. 


LITERATURE. 

The  following  list  comprises  some  of  the   more  important  sources  of 
information  as  to  the  rocks  and  fossils  of  the  Jurassic  series  : — 

(1)  '  Geology  of  Oxford  and  the  Thames  Valley.'     Phillips. 

(2)  'Geology  of  Yorkshire,' vol.  ii.     Phillips. 

(3)  '  Memoirs  of  the  Geological  Survey  of  Great  Britain.' 

(4)  '  Geology  of  Cheltenham.'     Murchison,  2d  ed.     Buckmr.n. 

(5)  Mntroduction  to  the  Monograph  of  the  Oolitic  AsteriadDs'  (Pabeon- 

tographical  Society).     Wright. 

(6)  "  Zone  of  Avicula  contorta  and  the  Lower  Lias  of  the  South  of 

England" — '  Quart.  Journ.  Geol.  Soc.,'  vol.  xvi.,  1860.    Wright. 

(7)  "  Oolites  of  Northamptonshire" — '  Quart.  Journ.  Geol.  Soc.,' vols. 

xxvi.  and  xxix.     Sharp. 

(8)  'Manual  of  Geology.'     Dana. 

(9)  'Derjura.'     Quenstedt. 

(10)   '  Das  Flotzgebirge  Wiirttembergs.'     Quenstedt. 
(n)   'Jura  Formation.'     Oppel. 


256  HISTORICAL   PALEONTOLOGY. 

(12)  '  Paleontologie  du  Departement  de  la  Moselle.'     Terquem. 

(13)  'Cours  elementaire  cle  Paleontologie.'     L)  Orbigny. 

(14)  '  Paleontologie  Frai^aise.'     D'Orbigny. 

(15)  'Fossil  Echinodermata  of  the  Oolitic  Formation'  (Palaeontographi- 

cal  Society).      Wright. 

(16)  '  Brachiopoda  of  the   Oolitic   Formation'    (Palaeontographical  So- 

ciety).    Davidson. 

(17)  '  Mollusca  of  the  Great  Oolite'  (Palaeontographical  Society).     Mor- 

ris and  Lycett. 

(18)  'Monograph  of  the  Fossil  Trigonise'  (Palaeontographical  Society). 

Lycett. 

(19)  'Corals   of  the    Oolitic    Formation'    (Palaeontographical  Society). 

Edwards  and  Haime. 

(20)  '  Supplement  to  the  Corals  of  the  Oolitic  Formation '  (Palceonto- 

graphical  Society).      Martin  Duncan. 

(21)  'Monograph    of    the    Belemnitidse '    (Palaeontographical    Society). 

Phillips. 

(22)  '  Structure  of  the  Belemnitidae  '  (Mem.  Geol.  Survey).     Huxley. 

(23)  '  Sur  les  Belemnites. '     Blainville. 

(24)  '  Cephalopoden.'     Quenstedt. 

(25)  '  Mineral  Conchology.'     Sowerby. 

(26)  'Jurassic  Cephalopoda' (Palaeontologica  Indica).     Waagen. 

(27)  'Manual  of  the  Mollusca.'     Woodward. 

(28)  'Petrefaktenkunde.'     Schlotheim. 

(29)  '  Bridgewater  Treatise.'     Buckland. 

(30)  '  Versteinerungen  des  Oolithengebirges.'     Roemer. 

(31)  'Catalogue  of  British  Fossils.'     Morris. 

(32)  '  Catalogue  of  Fossils  in  the  Museum  of  Practical  Geology.'    Ether- 

idge. 

(33)  '  Beitrage  zur  Petrefaktenkunde.'     Miinster. 

(34)  '  Petrefacta  Germaniae.'     Goldfuss. 

(35)  '  Lethaea  Rossica.'     Eichwald. 

(36)  '  Fossil  Fishes'  (Decades  of  the  Geol.  Survey).     Sir  Philip  Egerton. 

(37)  'Manual  of  Palaeontology.'     Owen. 

(38)  '  British  Fossil  Mammals  and  Birds.'     Owen. 

(39)  '  Monographs  of  the  Fossil  Reptiles  of  the  Oolitic  Formation '  (Palae- 

ontographical Society).     Owen. 

(40)  '  Fossil  Mammals  of  the  Mesozoic  Formations'  (Palaeontographical 

Society).     Owen. 

(41)  'Catalogue  of  Ornithosauria.'     Seeley. 

(42)  "Classification  of  the  Deinosauria  " — 'Quart.  Journ.  Geol.  Soc.,' 

vol.  xxvi.,  1870.     Huxley. 


CHAPTER    XVII. 

THE   CRETACEOUS  PERIOD, 

The  next  series  of  rocks  in  ascending  order  is  the  great  and 
important  series  of  the  Cretaceous  Rocks,  so  called  from  the 
general  occurrence  in  the  system  of  chalk  (Lat.  crcta,  chalk). 


THE  CRETACEOUS   PERIOD.  257 

As  developed  in  Britain  and  Europe  generally,  the  following 
leading  subdivisions  may  be  recognised  in  the  Cretaceous 
series  : — 

1.  Wealden,  )  T 

2.  Lower  Greensand  or  Neocomian,  '  Lower  Cetaceous. 


3.  Gault, 

4.  Upper  Greensand, 

5.  Chalk, 

6.  Maestricht  beds, 


Upper  Cretaceous. 


I.  Wealden. — The    Wealden  formation,  though  of  consider- 
able importance,  is  a  local  group,  and  is  confined  to  the  south- 
east of  England,  France,  and  some  other  parts  of  Europe.     Its 
name  is  derived  from  the  Weald,  a  district  comprising  parts  of 
Surrey,  Sussex,  and  Kent,  where  it  is  largely  developed.     Its 
lower  portion,  for  »a  thickness  of  from   500  to   1000  feet,  is 
arenaceous,  and  is  known  as  the  Hastings  Sands.     Its  Upper 
portion,  for  a  thickness  of  150  to  nearly  300  feet,  is  chiefly 
argillaceous,  consisting  of  clays  with  sandy  layers,  and  occa- 
sionally courses  of  limestone.     The  geological  importance  of 
the  Wealden  formation  is  very  great,  as  it  is  undoubtedly  the 
delta  of  an  ancient  river,  being  composed  almost  wholly  of 
fresh-water  beds,  with  a  few  brackish- water  and  even  marine 
strata,   intercalated   in  the   lower   portion.     Its   geographical 
extent,  though  uncertain,  owing  to  the  enormous  denudation 
to  which  it  has  been  subjected,  is  nevertheless  great,  since  it 
extends  from  Dorsetshire  to  France,  and  occurs  also  in  North 
Germany.     Still,  even  if  it  were  continuous  between  all  these 
points,  it  would  not  be  larger  than  the  delta  of  such  a  modern 
river  as  the  Ganges.     The  river  which  produced  the  Wealden 
series  must  have  flowed  from  an  ancient  continent  occupying 
what  is  now  the  Atlantic  Ocean ;  and  the  time  occupied  in 
the  formation   of  the  Wealden  must  have  been  very  great, 
though  we  have,  of  course,  no  data  by  which  we  can  accurately 
calculate  its  duration. 

The  fossils  of  the  Wealden  series  are,  naturally,  mostly  the 
remains  of  such  animals  as  we  know  at  the  present  day  as  in- 
habiting rivers.  We  have,  namely,  fresh-water  Mussels  ( Unto), 
River-snails  (Paludina),  and  other  fresh  -  water  shells,  with 
numerous  little  bivalved  Crustaceans,  and  some  fishes. 

II.  Lower   Greensand  (Neocomien    of    D'Orbigny).  —  The 
Wealden  beds  pass  upward,  often  by  insensible  gradations, 
into  the  Lower  Greensand.     The  name  Lower  Greensand  is 
not  an  appropriate  one,  for  green  sands  only  occur  sparingly 
and  occasionally,  and  are  found  in  other  formations.     For  this 


258  HISTORICAL   PALEONTOLOGY. 

reason  it  has  been  proposed  to  substitute  for  Lower  Green  sand 
the  name  Nwc&mian,  derived  from  the  town  of  Neufchatel — 
anciently  called  Neocomum  —  in  Switzerland.  If  this  name 
were  adopted,  as  it  ought  to  be,  the  Wealden  beds  would  be 
called  the  Lower  Neocomian. 

The  Lower  Greensand  or  Neocomian  of  Britain  has  a  thick- 
ness of  about  850  feet,  and  consists  of  alternations  of  sands, 
sandstones,  and  clays,  with  occasional  calcareous  bands.  The 
general  colour  of  the  series  is  dark  brown,  sometimes  red  ;  and 
the  sands  are  occasionally  green,  from  the  presence  of  silicate 
of  iron. 

The  fossils  of  the  Lower  Greensand  are  purely  marine,  and 
among  the  most  characteristic  are  the  shells  of  Cephalopods. 

The  most  remarkable  point,  however,  about  the  fossils  of 
the  Lower  Cretaceous  series,  is  their  marked  divergence  from 
the  fossils  of  the  Upper  Cretaceous  rocks.  '  "Of  280  species  of 
fossils  in  the  Lower  Cretaceous  series,  only  51,  or  about  18 
per  cent,  pass  on  into  the  Upper  Cretaceous.  This  break  in 
the  life  of  the  two  periods  is  accompanied  by  a  decided  phy- 
sical break  as  well ;  for  the  Gault  is  often,  if  not  always,  un- 
conformably  superimposed  on  the  Lower  Greensand.  At  the 
same  time,  the  Lower  and  Upper  Cretaceous  groups  form  a 
closely- connected  and  inseparable  series,  as  shown  by  a  com- 
parison of  their  fossils  with  those  of  the  underlying  Jurassic 
rocks  and  the  overlying  Tertiary  beds.  Thus,  in  Britain  no 
marine  fossil  is  known  to  be  common  to  the  marine  beds  of 
the  Upper  Oolites  and  the  Lower  Greensand ;  and  of  more 
than  500  species  of  fossils  in  the  Upper  Cretaceous  rocks, 
almost  every  one  died  out  before  the  formation  of  the  lowest 
Tertiary  strata,  the  only  survivors  being  one  Brachiopod  and  a 
few  Foraminifera. 

III.  Gault  (Aptien  of  D'Orbigny). — The  lowest  member  of 
the  Upper  Cretaceous  series  is  a  stiff,   dark -grey,  blue,  or 
brown  clay,  often  worked  for  brick-making,  and  known  as  the 
Gault,  from  a  provincial  English  term.     It  occurs  chiefly  in 
the  south-east  of  England,  but  can  be  traced  through  France 
to  the  flanks  of  the  Alps  and  Bavaria.     It  never  exceeds  100 
feet  in   thickness  ;  but  it  contains  many  fossils,  usually  in   a 
state  of  beautiful  preservation. 

IV.  Upper  Greensand  (Albien  of  D'Orbigny;    Unterquader 
and  Lower  Pldnerkalk  of  Germany). — The  Gault  is  succeeded 
upward  by  the    Upper  Greensand,  which  varies  in  thickness 
from  3  up  to  100  feet,  and  which  derives  its  name  from  the 
occasional  occurrence  in  it  of  green  sands.     These,  however, 
are    local    and    sometimes    wanting,  and    the    name  "  LTpper 


THE   CRETACEOUS    PERIOD.  259 

Greensand  "  is  to  be  regarded  as  a  name  and  not  a  description. 
The  group  consists,  in  Britain,  of  sands  and  clays,  sometimes 
with  bands  of  calcareous  grit  or  siliceous  limestone,  and  occa- 
sionally containing  concretions  of  phosphate  of  lime,  which  are 
largely  worked  for  agricultural  purposes. 

V.  White  Chalk. — The  top  of  the  Upper  Greensand  be- 
comes argillaceous,  and  passes  up  gradually  into  the  base  of 
the  great  formation   known  as  the  true   Chalk,  divided  into 
the  three  subdivisions  of  the  chalk-marl,  white  chalk  without 
flints,  and  white  chalk  with  flints.     The  first  of  these  is  sim- 
ply argillaceous  chalk,  and   passes  up  into  a  great   mass  of 
obscurely- stratified  white  chalk  in  which  there  are  no  flints 
(Turonien  of  D'Orbigny;  Mittdquader  of  Germany).     This,  in 
turn,  passes  up  into  a  great  mass  of  white  chalk,  in  which  the 
stratification  is  marked  by  nodules  of  black  flint  arranged  in 
layers  (Senonien  of  D'Orbigny  ;   Oberquader  of  Germany).    The 
thickness  of  these  three  subdivisions  taken  together  is  some- 
times over  1000  feet,  and  their  geographical  extent  is  very 
great.     White  Chalk,  with  its  characteristic  appearance,  may 
be  traced  from  the  north  of  Ireland  to  the  Crimea,  a  distance 
of  about  1 140  geographical  miles ;  and,  in  an  opposite  direction, 
from  the  south  of  Sweden  to  Bordeaux,  a  distance  of  about 
840  geographical  miles. 

VI.  In  Britain  there  occur  no  beds  containing  Chalk  fossils, 
or  in  any  way  referable  to  the  Cretaceous  period,  above  the 
true  White   Chalk  with  flints.     On  the  banks  of  the  Maes, 
however,  near  Maastricht  in  Holland,  there  occurs  a  series  of 
yellowish  limestones,  of  about  100  feet  in  thickness,  and  un- 
doubtedly superior  to  the  White  Chalk.     These  Maastricht 
beds  (Danien  of  D'Orbigny)  contain  a  remarkable  series  of 
fossils,   the  characters   of  which  are    partly   Cretaceous  and 
partly  Tertiary.     Thus,  with  the  characteristic  Chalk  fossils, 
Belcmnites.  Baculites,  Sea-Urchins,  &c.,  are  numerous  Univalve 
Molluscs,  such  as  Cowries  and  Volutes,  which  are  otherwise 
exclusively  Tertiary  or  Recent. 

Holding  a  similar  position  to  the  Maestricht  beds,  and 
showing  a  similar  intermixture  of  Cretaceous  forms  with  later 
type.s,  are  certain  beds  which  occur  in  the  island  of  Seeland, 
in  Denmark,  and  which  are  known  as  the  Faxoe  Limestone. 

Of  a  somewhat  later  date  than  the  Maestricht  beds  is  the 
Pisolitic  Limestone  of  France,  which  rests  unconformably  on 
the  White  Chalk,  and  contains  a  large  number  of  Tertiary 
fossils  along  with  some  characteristic  Cretaceous  types. 

The  subjoined  sketch-section  exhibits  the  general  succession 
of  the  Cretaceous  deposits  in  Britain  :  — 


26Q 


HISTORICAL  PALAEONTOLOGY. 


GENERALISED  SECTION  OF  THE  CRETACEOUS  SERIES 
OF  BRITAIN. 


Fig  185. 


Eocene. 


3     ;= 


White  Chalk  with  Flints. 


.    >> White  Chalk  without  Flints. 

Chalk  Marl. 
Upper  Greensancl. 

Gault. 


Lower    Greensancl  or  Neo- 
comian. 


Weald  Clay. 

Wealden  Series. 

-  Hastings  Sands. 


In  North  America,  strata  of  Lower  Cretaceous  age  are  well 
represented  in  Missouri,  Wyoming,  Utah,  and  in  some  other 
areas;  but  the  greater  portion  of  the  American  deposits  of 
this  period  are  referable  to  the  Upper  Cretaceous.  The  rocks 
of  this  series  are  mostly  sands,  clays,  and  limestones — CJialk 
itself  being  unknown  except  in  Western  Arkansas.  Amongst 
the  sandy  accumulations,  one  of  the  most  important  is  the  so- 


THE   CRETACEOUS   PERIOD.  26l 

called  "  marl "  of  New  Jersey,  which  is  truly  a  "  Greensand," 
and  contains  a  large  proportion  of  glauconite  (silicate  of  iron 
and  potash).  It  also  contains  a  little  phosphate  of  lime,  and  is 
largely  worked  for  agricultural  purposes.  The  greatest  thick- 
ness attained  by  the  Cretaceous  rocks  of  North  America  is 
about  9000  feet,  as  in  Wyoming,  Utah,  and  Colorado.  Ac- 
cording to  Dana,  the  Cretaceous  rocks  of  the  Rocky  Mountain 
territories  pass  upwards  "without  interruption  into  a  coal- 
bearing  formation,  several  thousand  feet  thick,  on  which  the 
following  Tertiary  strata  lie  unconformably."  The  lower  por- 
tion of  this  "Lignitic  formation"  appears  to  be  Cretaceous, 
and  contains  one  or  more  beds  of  Coal;  but  the  upper  part  of  it 
perhaps  belongs  to  the  Lower  Tertiary.  In  America,  therefore, 
the  lowest  Tertiary  strata  appear  to  rest  conformably  upon  the 
highest  Cretaceous ;  whereas  in  Europe,  the  succession  at  this 
point  is  invariably  an  unconformable  one.  Owing,  however,  to 
the  fact  that  the  American  "Lignitic  formation"  is  a  shallow- 
water  formation,  it  can  hardly  be  expected  to  yield  much 
material  whereby  to  bridge  over  the  great  palaeontological  gap 
between  the  White  Chalk  and  Eocene  in  the  Old  World. 

Owing  to  the  fact  that  so  large  a  portion  of  the  Cretaceous 
formation  has  been  deposited  in  the  sea,  much  of  it  in  deep 
water,  the  plants  of  the  period  have  for  the  most  part  been 
found  special  members  of  the  series,  such  as  the  Wealden  beds, 
the  Aix-la-Chapelle  sands,  and  the  Lignitic  beds  of  North 
America.  Even  the  purely  marine  strata,  however,  have 
yielded  plant-remains,  and  some  of  these  are  peculiar  and 
proper  to  the  deep-sea  deposits  of  the  series.  Thus  the  little 
calcareous  discs  termed  "  coccoliths,"  which  are  known  to  be 
of  the  nature  of  "calcareous  sea-weeds  (A/gce)  have  been  de- 
tected in  the  White  Chalk  ;  and  the  flints  of  the  same  forma- 
tion commonly  contain  the  spore-cases  of  the  microscopic 
Desmids  (the  so-called  Xanthidia),  along  with  the  siliceous  cases 
of  the  equally  diminutive  Diatoms. 

The  plant-remains  of  the  Lower  Cretaceous  greatly  resemble 
those  of  the  Jurassic  period,  consisting  mainly  of  Ferns,  Cy- 
cads,  and  Conifers.  The  Upper  Cretaceous  rocks,  however, 
bothvin  Europe  and  in  North  America,  have  yielded  an  abun- 
dant flora  which  resembles  the  existing  vegetation  of  the  globe 
in  consisting  mainly  of  Angiospermous  Exogens  and  of  Mono- 
cotyledons.* In  Europe  the  plant-remains  in  question  have 

*  The  "Flowering  plants"  are  divided  into  the  two  great  groups  of  the 
Endogens  and  Exogens.  The  Endogens  (such  as  Grasses,  Palms,  Lilies, 
&c.)  have  no  true  bark,  nor  rings  of  growth,  and  the  stem  is  said  to  be 
"endogenous  ;  "  the  young  plant  also  possesses  but  a  single  seed-leaf  or 


262  HISTORICAL   PALAEONTOLOGY. 

been  found  chiefly  in  certain  sands  in  the  neighbourhood  of  Aix- 
la-Chapelle,  and  they  consist  of  numerous  Ferns,  Conifers  (such 
as  Cycadopteris),  Screw  P'mes(Pandamts),  Oaks  (Quercus\  Wal- 
nut (Jiiglans),  Fig  (Ficus),  and  many  Proteacea,  some  of  which  are 
referred  to  existing  genera  (Dryandra,  Banksia,  Grevillea,  &c.) 

In  North  America,  the  Cretaceous  strata  of  New  Jersey, 
Alabama,  Nebraska,  Kansas,  &c.,  have  yielded  the  remains  of 
numerous  plants,  many  of  which  belong  to  existing  genera. 
Amongst  these  may  be  mentioned  Tulip-trees  (Liriodendroti), 
Sassafras  (fig.  186),  Oaks  (Quenus),  Beeches  (Fagjis),  Plane- 
trees  (Platanus),  Alders  (A/nus),  Dog-wood  (Com us),  Willows 
(Salix),  Poplars  (Populus),  Cypresses  (dtpressus},  Bald  Cy- 
presses (Taxodium),  Magnolias,  &c.  Besides  these,  however, 
there  occur  other  forms  which  have  now  entirely  disappeared 
from  North  America — as,  for  example,  species  of  Cinnainoinuin 
and  Araucaria. 

It  follows  from  the  above,  that  the  Lower  and  Upper  Creta- 
ceous rocks  are,  from  a  botanical  point  of  view,  sharply  sepa- 
rated from  one  another.  The  Palaeozoic  period,  as  we  have 
seen,  is  characterised  by  the  prevalance  of  "  Flowerless  "  plants 
(Cryptogams),  its  higher  vegetation  consisting  almost  exclu- 
sively of  Conifers.  The  Mesozoic  period,  as  a  whole,  is  charac- 
terised by  the  prevalence  of  the  Cryptogamic  group  of  the 
Ferns,  and  the  Gymnospermic  groups  of  the  Conifers  and  the 
Cycads.  Up  to  the  close  of  the  Lower  Cretaceous,  no  Angio- 
spermous  Exogens  are  certainly  known  to  have  existed,  and 
Monocotyledonous  plants  or  Endogens  are  very  poorly  repre- 
sented. With  the  Upper  Cretaceous,  .however,  a  new  era  of 
plant-life,  of  which  our  present  is  but.  the  culmination,  com- 
menced, with  a  great  and  apparently  sudden  development  of  new 
forms.  In  place  of  the  Ferns,  Cycads,  and  Conifers  of  the  earlier 
Mesozoic  deposits,  we  have  now  an  astonishingly  large  number 
of  true  Angiospermous  Exogens,  many  of  them  belonging  to 
existing  types ;  and  along  with  these  are  various  Monocotyle- 
donous plants,  including  the  first  examples  of  the  great  and  im- 

"cotyledon."  Hence  these  plants  are  often  simply  called  "Monocotyledons" 
The  Exogens,  on  the  other  hand,  have  a  true  bark  ;  and  the  stem  increases 
by  annual  additions- to  the  outside,  so  that  rings  of  growth  are  produced. 
The  young  plant  has  two  seed-leaves  or  "cotyledons,"  and  these  plants 
are  therefore  called  "Dicotyledons"  Amongst  the  Exogens,  the  Pines 
(Conifers]  and  the  Cycads  have  seeds  which  are  unprotected  by  a  seed- 
vessel,  and  they  are  therefore  called  "  Gynmosperms. "  All  the  other 
Exogens,  including  the  ordinary  trees,  shrubs,  and  flowering  plants,  have 
the  seeds  enclosed  in  a  seed-vessel,  and  are  therefore  called  "Anglo- 
sperms.''1  The  derivation  of  these  terms  will  be  found  in  the  Glossary  at 
the  end  of  the  volume. 


THE  CRETAOEOUS   PERIOD. 


263 


portant  group  of  the  Palms.     It  is  thus  a  matter  of  interest  to 
reflect  that  plants  closely  related  to  those  now  inhabiting  the 


Fig.  i  £6  — Cretaceous  Angiosperms.     a,  Sassafras  Cretacenm;  b,  Liriodendron 
iMeekji',  c,  Legrtminosites  Marcouanus  ;  d,  Salix  Meekii.     (After  Dana.) 

earth,  were  in  existence  at  a  time  when  the  ocean  was  tenanted 
by  Ammonites  and  Belemnites,  and  when  land  and  sea  and 
air  were  peopled  by  the  extraordinary  extinct  Reptiles  of  the 
Mesozoic  period. 

As  regards  animal  life,  the  Protozoans  of  the  Cretaceous 
period  are  exceedingly  numerous,  and  are  represented  by  Fora- 
minifera  and  Sponges.  As  we  have  already  seen,  the  White 
Chalk  itself  is  a  deep-sea  deposit,  almost  entirely  composed 
of  the  microscopic  shells  of  Foraminifers,  along  with  Sponge- 
spicules,  and  organic  debris  of  different  kinds  (see  p.  22,  fig.  7). 
The  green  grains  which  are  so  abundant  in  several  minor  sub- 
divisions of  the  Cretaceous,  are  also  in  many  instances  really 
casts  in  glauconite  of  the  chambered  shells  of  these  minute 
organisms.  A  great  many  species  of  Foraminifera  have  been 
recognised  in  the  Chalk ;  but  the  three  principal  genera  are 


264  HISTORICAL   PALEONTOLOGY. 

Globigeriria,  Rotalia  (fig.  187),  and  Textularia — groups  which 
are  likewise  characteristic  of  the  "  ooze  "  of  the  Atlantic  and 


Fig.  187. — Rotalia  Boueana. 

Pacific  Oceans  at  great  depths.  The  flints  of  the  Chalk  also 
commonly  contain  the  shells  of  Foraminifera.  The  Upper 
Greensand  has  yielded  in  considerable  numbers  the  huge 
Foraminifera  described  by  Dr  Carpenter  under  the  name  of 
Parkeria,  the  spherical  shells  of  which  are  composed  of  sand- 
grains  agglutinated  together,  and  sometimes  attain  a  diameter 
of  two  and  a  quarter  inches.  The  Cretaceous  Sponges  are 
extremely  numerous,  and  occur  under  a  great  number  of  varie- 
ties of  shape  and  structure ;  but  the  two  most  characteristic 
genera  are  Siphonia  and  Ventriculites,  both  of  which  are  ex- 
clusively confined  to  strata  of  this  age.  The  SiphonicE  (fig. 
1 88)  consist  of  a  pear-shaped,  sometimes  lobed  head,  supported 
by  a  longer  or  shorter  stem,  which  breaks  up  at  its  base  into  a 
number  of  root-like  processes  of  attachment.  The  water  gained 
access  to  the  interior  of  the  Sponge  by  a  number  of  minute 
openings  covering  the  surface,  and  ultimately  escaped  by  a 
single,  large,  chimney- shaped  aperture  at  the  summit.  In  some 
respects  these  sponges  present  a  singular  resemblance  to  the 
beautiful  "  Vitreous  Sponges  "  (ffoltenia  or  Pheronema)  of  the 
deep  Atlantic  ;  and,  like  these,  they  were  probably  denizens 
of  a  deep  sea.  The  Ventriculites  of  the  Chalk  (fig.  189)  is, 
hovveyer,  a  genus  still  more  closely  allied  to  the  wonderful 
flinty  Sponges,  which  have  been  shown,  by  the  researches  of 
the  Porcupine,  Lightning,  and  Challenger  expeditions,  to  live 
half  buried  in  the  calcareous  ooze  of  the  abysses  of  our  great 
oceans.  Many  forms  of  this  genus  are  known,  having  "  usu- 
ally the  form  of  graceful  vases,  tubes,  or  funnels,  variously 
ridged  or  grooved,  or  otherwise  ornamented  on  the  surface, 
frequently  expanded  above  into  a  cup-like  lip,  and  continued 
below  into  a  bundle  of  fibrous  roots.  The  minute  structure  of 
these  bodies  shows  an  extremely  delicate  tracery  of  fine  tubes, 
sometimes  empty,  sometimes  filled  with  loose  calcareous  mat- 


THE   CRETACEOUS    PERIOD. 


265 


ter  dyed  with  peroxide  of  iron."— (Sir  Wyville  Thomson.) 
Many  of  the  Chalk  sponges,  originally  calcareous,  have  been 
converted  into  flint  subsequently  ;  but  the  Ventriculites  are 


Fig.  188. — Siphoniaficus. 
Upper  Greensand,  Europe. 


Fig.  189. —  Ventriculites  simplex. 
White  Chalk,  Britain. 


really  composed  of  this  substance,  and  are  therefore  genuine 
"Siliceous  Sponges,"  like  the  existing  Venus's  Flower-Basket 
(Euplectella).  Like  the  latter,  the  skeleton  was  doubtless  ori- 
ginally composed,  in  the  young  state,  of  disconnected  six- 
rayed  spicules,  which  ultimately  become  fixed  together  to 
constitute  a  continuous  frame-work.  The  sea-water,  as  in  the 
recent  forms,  must  have  been  admitted  to  the  interior  of  the 
Sponge  by  numerous  apertures  on  its  exterior,  subsequently 
escaping  by  a  single  large  opening  at  its  summit. 

Amongst  the  Ccelenteratcs,  the  "  Hydroid  Zoophytes "  are 
represented  by  a  species  of  the  encrusting  genus  Hydractinia, 
the  horny  polypary  of  which  is  so  commonly  found  at  the 
present  day  adhering  to  the  exterior  of  shells.  The  occurrence 
of  this  genus  is  of  interest,  because  it  is  the  first  known  instance 
in  the  entire  geological  series  of  the  occurrence  of  an  unques- 
tionable Hydroid  of  a  modern  type,  though  many  of  the  exist- 
ing forms  of  these  animals  possess  structures  which  are  per- 


266  HISTORICAL   PALAEONTOLOGY. 

fectly  fitted  for  preservation  in  the  fossil  condition.  The  corals 
of  the  Cretaceous  series  are  not  very  numerous,  and  for  the 
most  part  are  referable  to  types  such  as  Trochocyathus,  Stephano- 
phyllia,  Parasmilia,  Synhelia  (fig.  190),  <S:c.,  which  belong  to 
the  same  great  group  of  corals  as  the  majority  of  existing 


Fig.  190.  —SynJieUa  Sharpeana.     Chalk,  England. 

forms.  We  have  also  a  few  "  Tabulate  Corals "  (Polytre- 
macis\  hardly,  if  at  all,  generically  separable  from  very  ancient 
forms  (Heliolites)\  and  the  Lower  Greensand  has  yielded  the 
remains  of  the  little  Holocystis  elegans,  long  believed  to  be  the 
last  of  the  great  Palaeozoic  group  of  the  Rugosa. 

As  regards  the  Echinoderms,  the  group  of  the  Crinoids  now 
exhibits  a  marked  decrease  in  the  number  and  variety  of  its 
types.  The  "  stalked  "  forms  are  represented  by  Pentacri?ms 
and  Bourgueticrinus,  and  the  free  forms  by  Feather-stars  like 
our  existing  Comatulcz ;  whilst  a  link  between  the  stalked  and 
free  groups  is  constituted  by  the  curious  "  Tortoise  Encrinite 
(Marsupites).  By  far  the  most  abundant  Cretaceous  Echino- 
derms, however,  are  Sea-urchins  (Echinoids) ;  though  several 
Star-fishes  are  known  as  well.  The  remains  of  Sea-urchins  are 
so  abundant  in  various  parts  of  the  Cretaceous  series,  especi- 
ally in  the  White  Chalk,  and  are  often  so  beautifully  preserved, 
that  they  constitute  one  of  the  most  marked  features  of  the 
fauna  of  the  period.  From  the  many  genera  of  Sea-urchins 
which  occur  in  strata  of  this  age,  it  is  difficult  to  select  char- 
acteristic types;  but  the  genera  Galcrites  (fig.  191),  Discoidea 
(fig.  192),  Micrasfcr,  Ananchytes,  Diadcma,  Salcnia^  and  Ci- 


THE   CRETACEOUS   PERIOD. 


267 


daris,  may  be  mentioned  as  being  all  important  Cretaceous 


groups. 


JUJJS. 

Coming  to  the  Annulose  Animals  of  the  Cretaceous  period. 


Fig.  IQI. — Galeriies  albogalertts,  viewed  frorn  below,  from  the  side,  and  from  above. 
White  Chalk. 

there  is  little  special  to  remark.     The   Crustaceans  belong  for 
the  most  part  to  the  highly-organised  groups  of  the  Lobsters 


;.  192. — Discoidea  cylindrica  ',  under,  side,  and  upper  aspect. 
Upper  Greensand. 

and  the  Crabs  (the  Macrurous  and  Brachyurous  Decapods) ; 
but  there  are  also  numerous  little  Ostracodes,  especially  in  the 
fresh-water  strata  of  the  Wealden.  It  should  further  be  noted 
that  there  occurs  here  a.  great  development  of  the  singular 
Crustaceans  family  of  the  Barnacles  (Lepadida),  whilst  the  allied 
family  of  the  equally  singular  Acorn-shells  (Balanida)  is  feebly 
represented  as  well. 

Passing  on  to  the  Mollusca,  the  class  of  the  Sea-mats  and 
Sea-mosses  (Poly  zoo)  is  immensely  developed  in  the  Cretaceous 
period,  nearly  two  hundred  species  being  known  to  occur  in 
the  Chalk.  Most  of  the  Cretaceous  forms  belong  to  the  family 
of  the  Escharida,  the  genera  Eschar  a  and  Eschar ina  (fig.  193) 
being  particularly  well  represented.  Most  of  the  Cretaceous 
Polyzoans  are  of  small  size,  but  some  attain  considerable  di- 
mensions, and  many  simulate  Corals  in  their  general  form  and 
appearance. 


268 


HISTORICAL   PALAEONTOLOGY. 


The  Lamp-shells  (Brachiopods)  have  now  reached  a  further 
stage  of  the  progressive  decline,  which  they  have  been  under- 

going ever  since  the  close  of 
the  Palaeozoic  period.  Though 
individually  not  rare,  especially 
in  certain  minor  subdivisions 
of  the  series,  the  '  number  of 
generic  types  has  now  be- 
come distinctly  diminished,  the 
principal  forms  belonging  to 
the  genera  Tcrcbratuia,  Tere- 
bratdla  (fig.  194),  Terebratidina^ 
Rhynchonella,  and  Crania  (fig. 


193.—  A  small  fragment  of  Escharhui       lOS).          Ill    tllC    last    mentioned 
Oceani,  of  the  natural  size  ;  and  a  portion          r      i  ^i  i      11     ••  i       j 

of  the  same  enlarged.    Upper  Greensand.       OI    tllCSC,    the    shell    IS    attached 

to  foreign   bodies  by  the  sub- 

stance of  one  of  the  valves  (the  ventral),  whilst  the  other  or 
free  valve  is  more  or  less  limpet  shaped.     All  the  above-men- 


Fig.  194.  —  Terebra.tclla  Astier'ana.     Cault. 

tioned  genera  are  in  existence  at  the  present  day;  and  one 
species — namely,  Terebratidina  striata — appears  to  be  undis- 
tinguishable  from  one  now  living — the  Terebratidina  caput- 
serpentis. 

Whilst  the  Lamp-shells  are  slowly  declining,  the  Bivalves 
(Lamellibranchs}  are  greatly  developed,  and  are  amongst  the 
most  abundant  and  characteristic  fossils  of  the  Cretaceous 
period.  In  the  great  river-deposit  of  the  Wealden,  the  Bivalves 
are  forms  proper  to  fresh  water,  belonging  to  the  existing 
River-mussels  (Unio\  Cyrena  and  Cyclas ;  but  most  of  the 
Cretaceous  Lamellibranchs  are  marine.  Some  of  the  most 
abundant  and  characteristic  of  these  belong  to  the  great  family 
of  the  Oysters  (Ostreidcz).  Amongst  these  are  the  genera 
Gryphcea  and  Exogyra,  both  of  which  we  have  seen  to  occur 


THE  CRETACEOUS    PERIOD. 


269 


abundantly  in  the  Jurassic ;  and  there  are  also  numerous  true 
Oysters  (Ostrea,  fig.  196)  and  Thorny  Oysters  (Spondylus,  fig. 


Fijf.  195. — Crania  Ignabergensis.  The  left-hand  figure  shows  the  perfect  shell,  at- 
tached by  its  ventral  valve  to  a  foreign  body;  the  middle  figure  shows  the  exterior  of  the 
limpet-shaped  dorsal  valve  ;  and  the  right-hand  figure  represents  the  interior  of  the  at- 
tached valve.  White  Chalk. 

197).     The  genus  Trigonia,  so  characteristic  of  the  Mesozoic 
deposits  in  general,  is  likewise  well  represented  in  the  Creta- 


Fig.  196. — Ostrea  Cottloni.     Lower  Greensand. 

ceous  strata.  No  single  genus  of  Bivalves  is,  however,  so  highly 
characteristic  of  the  Cretaceous  period  as  Inocemmus,  a  group 
belonging  to  the  family  of  the  Pearl-mussels  (Aviculidce).  The 
shells  of  this  genus  (fig.  198)  have  the  valves  unequal  in  size, 
the  larger  valve  often  being  much  twisted,  and  both  valves 
being  marked  with  radiating  ribs  or  concentric  furrows.  The 
hinge-line  is  long  and  straight,  with  numerous  pits  for  the 
attachment  of  the  ligament  which  serves  to  open  the  shell. 
Some  of  the  Inoceraini  attain  a  length  of  two  or  three  feet,  and 
fragments  of  the  shell  are  often  found  perforated  by  boring 
19 


2/0 


HISTORICAL   PALAEONTOLOGY. 


Sponges.     Another  extraordinary  family  of  Bivalves,  which  is 
exclusively  confined  to  the  Cretaceous  rocks,  is  that  of  the 


Fig.  197. — Spcmdylus  spitwsus.     White  Chalk. 

Hippuritidce.     All  the  members  of  this  group  (fig.  199)  were 
attached  to  foreign  objects,  and  lived  associated  in  beds,  like 


Fig.  198.  —Jnoceramus  sukatus.     Gault. 

Oysters.  The  two  valves  of  the  shell  are  always  altogether 
unlike  in  sculpturing,  appearance,  shape,  and  size ;  and  the 
cast  of  the  interior  of  the  shell  is  often  extremely  unlike  the 
form  of  the  outer  surface.  The  type-genus  of  the  family  is 
Hippurites  itself  (fig.  199),  in  which  the  shell  is  in  the  shape  of 
a  straight  or  slightly-twisted  horn,  sometimes  a  foot  or  more  in 
length,  constituted  by  the  attached  lower  valve,  and  closed 
above  by  a  small  lid-like  free  upper  valve.  About  a  hundred 
species  of  the  family  of  the  Hippuritidce  are  known,  all  of  these 
being  Cretaceous,  and  occurring  in  Britain  (one  species  only), 
in  Southern  Europe,  the  West  Indies,  North  America,  Algeria, 
and  Egypt.  Species  of  this  family  occur  in  such  numbers  in 
certain  compact  marbles  in  the  south  of  Europe,  of  the  age  of 
the  Upper  Cretaceous  (Lower  Chalk),  as  to  have  given  origin 
to  the  name  of  "  Hippurite  Limestones,"  applied  to  these 
ctrata. 


THE   CRETACEOUS    PERIOD. 


271 


The  Univalves  (Gasteropods]  of  the  Cretaceous  period  are 
not  very  numerous,  nor  particularly  remarkable.  Along  with 
species  of  the  persistent  genus  Plcurofomaria  and  the  Meso- 


Fig.  i  go. — Hippurites  Toucasiana. 
A  large  individual,  with  two  smaller 
ones  attached  to  it.  Upper  Cretace- 
ous, South  of  Europe. 


Fig.  -2.<x>.  — Valuta  elongata. 
White  Chalk. 


zoic  Nerintza,  we  meet  with  examples  of  such  modern  types 
as  Turritella  and  Natica,  the  Staircase-shells  (Silarium],  the 
Wentle-traps  (Scalaria),  the  Carrier-shells  (P/wrus),  &c.  To- 
wards the  close  of  the  Cretaceous  period,  and  especially  in 
such  transitional  strata  as  the  Maestricht  beds,  the  Faxoe 
Limestone,  and  the  Pisolitic  Limestone  of  France,  we  meet 
with  a  number  of  carnivorous  ("  siphonostomatous ")  Uni- 
valves, in  which  the  mouth  of  the  shell  is  notched  or  pro- 
duced into  a  canal.  Amongst  these  it  is  interesting  to 
recognise  examples  of  such  existing  genera  as  the  Volutes 
(Valuta,  fig.  200),  the  Cowries  (Cyprcea],  the  Mitre-shells 
(Mitra),  the  Wing  -  shells  (Strombus],  the  Scorpion  -  shells 
(P.eroceras),  &c. 


2/2  HISTORICAL  PALEONTOLOGY. 

Upon  the  whole,  the  most  characteristic  of  all  the  Creta- 
ceous Molluscs  are  the  Cephalopods,  represented  by  the  remains 
of  both  Tetrabranchiate  and  Dibranchiate  forms.  Amongst  the 
former,  the  long-lived  genus  Nautilus  (fig.  201)  again  reap- 


Fig.  201. — Different  views  of  Nautilus  Danicus.     Faxoe  Limestone 
(Upper  Cretaceous),  Denmark. 

pears,  with  its  involute  shell,  its  capacious  body-chamber,  its 
simple  septa  between  the  air-chambers,  and  its  nearly  or  quite 
central  siphuncle.     The  majority  of  the  chambered   Cephalo- 
pods of  the  Cretaceous  belong,  however,  to  the  complex  and 
beautiful  family  of  the  Ammonitidce,  with  their  elaborately- 
folded  and  lobed  septa  and  dorsally-placed  siphuncle.     This 
family  disappears  wholly  at  the  close  of  the  Cretaceous  period ; 
but  its  approaching  extinction,  so  far  from  being  signalised  by 
any  slow  decrease  and  diminution  in  the  number  of  specific 
or  generic  types,  seems  to  have  been  attended  by  the  develop- 
ment of  whole  series  of  new  forms.     The  genus  Ammonites 
itself,  dating  from  the  Carboniferous,  has  certainly  passed  its 
prime,  but  it  is  still  represented  by  many  species,  and  some  of 
these  attained   enormous   dimensions   (two  or  three  feet  in 
diameter).     The  genus  Ancyloceras  (fig.  202),  though  likewise 
of  more  ancient  origin  (Jurassic),  is  nevertheless  very  charac- 
teristic of  the  Cretaceous.     In  this  genus  the  first  portion  of 
the  shell  is  in  the  form  of  a  flat  spiral,  the  coils  of  which  are 
not  in  contact ;  and  its  last  portion  is  produced  at  a  tangent, 
becoming  ultimately  bent  back  in  the  form  of  a  crosier.     Be- 
sides these   pre  -  existent   types,  the  Cretaceous  rocks   have 
yielded  a  great  number  of  entirely  new  forms  of  the  Ammoni- 
tida,  which  are  not  known  in  any  deposits  of  earlier  or  later 
date.     Amongst  the  more  important  of  these  may  be  men- 
tioned   Crioceras,    Turrililcs,    Scaphites,   Hamites,   Ptychoceras, 


THE   CRETACEOUS   PERIOD. 


2/3 


and  B acuities.     In  the  genus  Crioceras  (fig.  204,  d),  the  shell 
consists  of  an  open  spiral,  the  volutions  of  which  are  not  in 


Fig.  202 . — A  ncyloceras 


contact,  thus  resembling  a  partially-unrolled  Ammonite  or  the 
inner  portion  of  an  Ancyloceras.  In  -  Turrilites  (fig.  203),  the 
shell  is  precisely  like  that  of  the  Ammonite  in  its  structure ; 
but  instead  of  forming  a  flat  spiral,  it  is  coiled  into  an  ele- 
vated turreted  shell,  the  whorls  of  which  are  in  contact  with 
one  another.  In  the  genus  Scaphites  (fig.  204,  e),  the  shell 
resembles  that  of  Ancyloceras  in  consisting  of  a  series  of  volu- 
tions coiled  into  a  flat  spiral,  the  last  being  detached  from  the 
others,  produced,  and  ultimately  bent  back  in  the  form  of  a 
crosier;  but  the  whorls  of  the  enrolled  part  of  the  shell  are  in 
contact,  instead  of  being  separate  as  in  the  latter.  In  the 
genus  Hamites  (fig.  204, /),  the  shell  is  an  extremely  elongated 
cone,  which  is  bent  upon  itself  more  than  once,  in  a  hook-like 
manner,  all  the  volutions  being  separate.  The  genus  Ptycho- 
ceras  (fig.  204,  a)  is  very  like  Hamites,  except  that  the  shell  is 
only  bent  once ;  and  the  two  portions  thus  bent  are  in  contact 
with  one  another.  Lastly,  in  the  genus  Baculites  (fig.  204,  b 
and  c)  the  shell  is  simply  a  straight  elongated  cone,  not  bent 
in  any  way,  but  possessing  the  folded  septa  which  characterise 
the  whole  Ammonite  family.  The  Baculite  is  the  simplest  of 
.all  the  forms  of  the  Ammonitidce;  and  all  the  other  forms,  how- 
ever complex,  may  be  regarded  as  being  simply  produced  by 
the  bending  or  folding  of  such  a  conical  septate  shell  in  differ- 
ent ways.  The  Baculite,  therefore,  corresponds,  in  the  series 
of  the  Ammonitidce,  to  the  Orthoceras  in  the  series  of  the  Nau- 
tilidce.  All  the  above-mentioned  genera  are  characteristically, 
or  exclusively,  Cretaceous,  and  they  are  accompanied  by  a 
number  of  other  allied  forms,  which  cannot  be  noticed  here. 
Not  a  single  one  of  these  genera,  further,  has  hitherto  been 
detected  in  any  strata  higher  than  the  Cretaceous.  We  may 
therefore  consider  that  these  wonderful,  varied,  and  elaborate 


2/4 


HISTORICAL   PAL/EOXTOLOGY. 


forms  of  Ammoniiida  constitute  one  of  the  most  conspicuous 
features  in  the  life  of  the  Chalk  period. 

The  Dibranchiate  Cephalopods  are  represented  partly  by  the 


Fig.  203. —  Turrilitcs  cate- 
natus.  The  lower  figure  rep- 
resents the  entire  shell  ;  the 
upper  figure  represents  the 
base  of  the  shell  seen  from 
below.  Gault. 


Fig.  204. — a,  Ptychoceras  Emericlannm,  reduced 
—Lower  Greensand;  b,  Baculites  anceps,  reduced 
—  Chalk  ;  c,  Portion  of  the  same,  showing  the  folded 
edges  of  the  septa ;  d,  Crioceras  cristatum,  reduced 
—Gault  ;  e,  Scaphites  a-qnalis,  natural  size — Chalk  ; 
/,  Hamites  rotnndus,  restored— Gault. 


beak  like  jaws  of  unknown  species  of  Cuttle-fishes  and  partly 
by  the  internal  skeletons  of  Belemnites.  Amongst  the  latter, 
the  genus  Belemnites  itself  holds  its  place  in  the  lower  part  of 


THE  CRETACEOUS    PERIOD. 


275 


the  Cretaceous  series ;  but  it  disappears  in  the  upper  portion 
of  the  series,  and  its  place  is  taken  by  the  nearly-allied  genus 
Belemnitella  (fig.   205),  distinguished  by  the  possession  of  a 
straight  fissure  in  the  upper  end  of  the  guard.     This 
also    disappears   at  the    close   of  the    Cretaceous 
period;  and  no  member   of  the   great    Mesozoic 
family  of  the  Belemmtidce  has   hitherto  been  dis- 
covered in  any  Tertiary  deposit,  or  is  known  to 
exist  at  the  present  day. 

Passing  on  next  to  the  Vertebrate  Animals  of  the 
Cretaceous  period,  we  find  the  Fishes  represented 
as  before  by  the  Ganoids  and  the  Placoids,  to  which, 
however,  we  can  now  add  the  first  known  examples 
of  the  great  group  of  the  Bony  Fishes  or  Teleosteans, 
comprising  the  great  majority  of  existing  forms. 
The  Ganoid  fishes  of  the  Cretaceous  (Lepidotus, 
Pycnodus,  &c  )  present  no  features  of  special  in- 
terest. Little,  also,  need  be  said  about  the  Placoid 
fishes  of  this  period.  As  in  the  Jurassic  deposits, 
the  remains  of  these  consist  partly  of  the  teeth  of 
genuine  Sharks  (Lamna,  Odontaspis,&c.\  and  partly 
of  the  teeth  and  defensive  spines  of  Cestracionts, 
such  as  the  living  Port -Jackson  Shark.  The  pointed  and  sharp- 
edged  teeth  of  true  Sharks  are  very  abundant  in  some  beds,  such 
as  the  Upper  Greensand,  and  are  beautifully  preserved.  The 
teeth  of  some  forms  (CarchaHas,  &c.)  attain  occasionally  a 
length  of  three  or  four  inches,  and  indicate  the  existence  in  the 
Cretaceous  seas  of  huge  predaceous  fishes,  probably  larger  than 
any  existing  Sharks.  The  remains  of  Cestracionts  consist 
partly  of  the  flattened  teeth  of  genera  such  as  Acrodus  and 
Ptychodus  (the  latter  confined  to  rocks  of  this  age),  and  partly 
of  the  pointed  teeth  of  Hybodus,  a  genus  which  dates  from  the 
Trias.  In  this  genus  the  teeth  (fig.  206)  consist  of  a  principal 
central  cone,  flanked  by  minor  lateral  cones;  and  the  fin- 


Fig.  205.— 

Guard   of 
Belemnitflla 

mucronata. 
White  Chalk. 


Fig.  206.— Tooth 
of  Hybodus, 


Fig.  207. — Fin-spine  of  Hybodns.     Lower  Greensand. 


spines  (fig.  207)  are  longitudinally  grooved,  and  carry  a  series 
of  small  spines  on  their  hinder  or  concave  margin.     Lastly, 


276 


HISTORICAL   PALEONTOLOGY. 


the  great  modern  order  of  the  Bony  Fishes  or  Teleosteans 
makes  its  first  appearance  in  the  Upper  Cretaceous  rocks, 
where  it  is  represented  by  forms  belonging  to  no  less  than 
three  existing  groups  —  namely,  the  Salmon  family  (Sal- 
monidce],  the  Herring  family  (Clupeida),  and  the  Perch  family 
(Peradce).  All  these  fishes  have  thin,  horny,  overlapping 


Fig.  208. — i,  Beryx  Lewesiensis,  a  Percoid  fish  from  the  Chalk  ;  2,  Osmeroides 
Mantela,  a  Salmonoid  fish  from  the  Chalk. 

scales,  symmetrical  ("  homocercal")  tails,  and  bony  skeletons. 
The  genus  Beryx  (fig.  208,  i)  is  one  represented  by  existing 
species  at  the  present  day,  and  belongs  to  the  Perch  family. 
The  genus  Osmeroides,  again  (fig.  208,  2),  is  supposed  to  be 
related  to  the  living  Smelts  (Osmerus),  and,  therefore,  to 
belong  to  the  Salmon  tribe. 

No  remains  of  Amphibians  have  hitherto  been  detected  in 
any  part  of  the  Cretaceous  series ;  but  Reptiles  are  extremely 
numerous,  and  belong  to  very  varied  types.  As  regards  the 
great  extinct  groups  of  Reptiles  which  characterise  the  Meso- 
zoic  period  as  a  whole,  the  huge  "  Enaliosaurs "  or  "  Sea- 
Lizards  "  are  still  represented  by  the  Ichthyosaur  and  the 
Plesiosanr.  Nearly  allied  to  the  latter  of  these  is  the  Elas- 
mosaurus  of  the  American  Cretaceous,  which  combined  the 


THE   CRETACEOUS   PERIOD.  277 

long  tail  of  the  Ichthyosaur  with  the  long  neck  of  the  Plesio- 
saur.  The  length  of  this  monstrous  Reptile  could  not  have 
been  less  than  fifty  feet,  the  neck  consisting  of  over  sixty 
vertebrae  and  measuring  over  twenty  feet  in  length.  The 
extraordinary  Flying  Reptiles  of  the  Jurassic  are  likewise  well 
represented  in  the  Cretaceous  rocks  by  species  of  the  genus 
Pterodactyl  us  itself,  and  these  later  forms  are  much  more 
gigantic  in  their  dimensions  than  their  predecessors.  Thus 
some  of  the  Cretaceous  Pterosaurs  seem  to  have  had  a  spread 
of  wing  of  from  twenty  to  twenty-five  feet,  more  than  realising 
the  "  Dragons  "  of  fable  in  point  of  size.  The  most  remark- 
able, however,  of  the  Cretaceous  Pterosaurs  are  the  forms 
which  have  recently  been  described  by  Professor  Marsh  under 
the  generic  title  01"  Pteranodon.  In  these  singular  forms — so 
far  only  known  as  American — the  animal  possessed  a  skeleton 
in  all  respects  similar  to  that  of  the  typical  Pterodactyles, 
except  that  the  jaws  are  completely  destitute  of  teeth.  There 
is,  therefore,  the  strongest  probability  that  the  jaws  were 
encased  in  a  horny  sheath,  thus  coming  to  resemble  the  beak 
of  a  Bird.  Some  of  the  recognised  species  of  Pteranodon  are 
very  small ;  but  the  skull  of  one  species  (P.  longiccps]  is  not 
less  than  a  yard  in  length,  and  there  are  portions  of  the  skull 
of  another  species  which  would  indicate  a  length  of  four  feet 
for  the  cranium.  These  measurements  would  point  to  dimen- 
sions larger  than  those  of  any  other  known  Pterosaurs. 

The  great  Mesozoic  order  of  the  Deinosaurs  is  largely  rep- 
resented in  the  Cretaceous  rocks,  partly  by  genera  which 
previously  existed  in  the  Jurassic  period,  and  partly  by  entirely 
new  types.  The  great  delta-deposit  of  the  Wealden,  in  the 
Old  World,  has  yielded  the  remains  of  various  of  these  huge 
terrestrial  Reptiles,  and  very  many  others  have  been  found  in 
the  Cretaceous  deposits  of  North  America.  One  of  the  most 
celebrated  of  the  Cretaceous  Deinosaurs  is  the  Iguanodon,  so 
called  from  the  curious  resemblance  of  its  teeth  to  those  of  the 
existing  but  comparatively  diminutive  Iguana.  The  teeth  (fig. 
209)  are  soldered  to  the  inner  face  of  the  jaw,  instead  of  being 
sunk  in  distinct  sockets;  and  they  have  the  form  of  somewhat 
flattened  prisms,  longitudinally  ridged  on  the  outer  surface, 
with  an  obtusely  triangular  crown,  and  having  the  enamel 
crenated  on  one  or  both  sides.  They  present  the  extraordinary 
feature  that  the  crowns  became  worn  down  flat  by  mastication, 
showing  that  the  Iguanodon  employed  its  teeth  in  actually 
chewing  and  triturating  the  vegetable  matter  on  which  it  fed. 
There  can  therefore  be  no  doubt  but  that  the  Iguanodon,  in 
spite  of  its  immense  bulk,  was  an  herbivorous  Reptile,  and 


278 


HISTORICAL   PALEONTOLOGY. 


lived   principally   on   the   foliage   of   the    Cretaceou-s   forests 
amongst  which  it  dwelt.     Its  size  has  been  variously  estimated 


Fig.  209. — Teeth  of  Ignanodon  Mantellii.     Wealden,  Britain. 

at  from  thirty  to  fifty  feet,  the  thigh-bone  in  large  examples 
measuring  nearly  five  feet  in  length,  with  a  circumference  of 
twenty-two  inches  in  its  smallest  part.  With  the  strong  and 
massive  hind-limbs  are  associated  comparatively  weak  and 
small  fore-limbs  ;  and  there  seems  little  reason  to  doubt  that 
the  Ignanodon  must  have  walked  temporarily  or  permanently 
upon  its  hind-limbs,  after  the  manner  of  a  Bird.  This  conjec- 
ture is  further  supported  by  the  occurrence  in  the  strata  which 
contain  the  bones  of  the  Ignanodon  of  gigantic  three-toed  foot- 
prints, disposed  singly  in  a  double  track.  These  prints  have 
undoubtedly  been  produced  by  some  animal  walking  on  two 
legs;  and  they  can  hardly,  with  any  probability,  be  ascribed  to 
any  other  than  this  enormous  Reptile.  Closely  allied  to  the 
Iguanodon  is  the  Hadrosaurus  of  the  American  Cretaceous,  the 
length  of  which  is  estimated  at  twenty- eight  feet.  Ignanodon 
does  not  appear  to  have  possessed  any  integumentary  skeleton; 
but  the  great  Hylceosaurus  of  the  Wealden  seems  to  have  been 
furnished  with  a  longitudinal  crest  of  large  spines  running 
down  the  back,  similar  to  that  which  is  found  in  the  compara- 
tively small  Iguanas  of  the  present  day.  The  Megalosaurus  of 
the  Oolites  continued  to  exist  in  the  Cretaceous  period;  and,  as 
we  have  previously  seen,  it  was  carnivorous  in  its  habits.  The 
American  Lcelaps  was  also  carnivorous,  and,  like  the  Megalosaur, 


THE   CRETACEOUS   PERIOD.  279 

which  it  very  closely  resembles,  appears  to  have  walked  upon 
its  hind-legs,  the  fore-limbs  being  disproportionately  small. 

Another  remarkable  group  of  Reptiles,  exclusively  confined 
to  the  Cretaceous  series,  is  that  of  the  Mosasauroids,  so  called 
from  the  type-genus  Mosasaurus.  The  first  species  of  Mosa- 
saurus  known  to  science  was  the  M.  Camperi  (fig.  210),  the 


Fig.  210. — Skull  of  Mosasaurus  Camperi,  greatly  reduced      Maestricht  Chalk. 

skull  of  which — six  feet  in  length — was  discovered  in  1780  in 
the  Maestricht  Chalk  at  Maestricht.  As  this  town  stands  on 
the  river  Meuse,  the  name  of  Mosasaurus  ("  Lizard  of  the 
Meuse")  was  applied  to  this  immense  Reptile.  Of  late  years 
the  remains  of  a  large  number  of  Reptiles  more  or  less  closely 
related  to  Mosasaurus,  or  absolutely  belonging  to  it,  have  been 
discovered  in  the  Cretaceous  deposits  of  North  America,  and 
have  been  described  by  Professors  Cope  and  Marsh.  All 
the  known  forms  of  this  group  appear  to  have  been  of  large 
size — one  of  them,  Mosasaurus  princeps,  attaining  the  length  of 
seventy-five  or  eighty  feet,  and  thus  rivalling  the  largest  of  ex- 
isting Whales  in  its  dimensions.  The  teeth  in  the  "  Mosa- 
sauroids  "  are  long,  pointed,  and  slightly  curved ;  and  instead 
of  being  sunk  in  distinct  sockets,  they  are  firmly  amalgamated 
with  the  jaws,  as  in  modern  Lizards.  The  palate  also  carried 
teeth,  and  the  lower  jaw  was  so  constructed  as  to  allow  of  the 
mouth  being  opened  to  an  immense  width,  somewhat  as  in  the 
living  Serpents.  The  body  was  long  and  snake-like,  with  a 
very  long  tail,  which  is  laterally  compressed,  and  must  have 
served  as  a  powerful  swimming-apparatus.  In  addition  to  this, 
both  Dairs  of  limbs  have  the  bones  connecting  them  with  the 


280 


HISTORICAL   PALAEONTOLOGY. 


trunk  greatly  shortened ;  whilst  the  digits  were  enclosed  in  the 
integuments,  and  constituted  paddles,  closely  resembling  in 
structure  the  "  flippers"  of  Whales  and  Dolphins.  The  neck 
is  sometimes  moderately  long,  but  oftener  very  short,  as  the 
great  size  and  weight  of  the  head  wouLd  have  led  one  to  anti- 
cipate. Bony  plates  seem  in  some  species  to  have  formed  an 
at  any  rate  partial  covering  to  the  skin ;  but  it  is  not  certain 
that  these  integumentary  appendages  were  present  in  all.  Up- 
on the  whole,  there  can  be  no  doubt  but  that  the  Mosasauroid 
Reptiles — the  true  "  Sea-serpents  "  of  the  Cretaceous  period — • 
were  essentially  aquatic  in  their  habits,  frequenting  the  sea, 
and  only  occasionally  coming  to  the  land. 

The  "  Mosasauroids  "  have  generally  been  regarded  as  a 
greatly  modified  group  of  the  Lizards  (Lacertilia).  Whether 
this  reference  be  correct  or  not — and  recent  investigations 
render  it  dubious — the  Cretaceous  rocks  have  yielded  the 
remains  of  small  Lizards  not  widely  removed  from  existing 
forms.  The  recent  order  of  the  Chdonians  is  also  represented 

in  the  Cretaceous  rocks, 
by  forms  closely  re- 
sembling living  types. 
Thus  the  fresh  -  water 
deposits  of  the  Wealden 
have  yielded  examples 
of  the  "Terrapins"  or 
"  Mud-Turtles"  (Emys); 
and  the  marine  Creta- 
ceous strata  have  been 
found  to  contain  the 
remains  of  various  spe- 
cies of  Turtles,  one  of 
which  is  here  figured 
(fig.  211).  No  true 
Serpents  ( (9//«V//#  )have 
as  yet  been  detected  in 
the  Cretaceous  rocks; 
and  this  order  does  not 
appear  to  have  come 
into  existence  till  the 
Tertiary  period.  Last- 
ly, true  Crocodiles  are 
known  to  have  existed 
in  considerable  num- 
bers in  the  Cretaceous  period.  The  oldest  of  these  occur 
in  the  fresh-water  deposit  of  the  WTealden;  and  they  differ  from 


Fig.  211. — Carapace  of  Chelone  Benstedi. 
Lower  Chalk.     (After  Owen.) 


THE  CRETACEOUS   PERIOD.  28 1 

the  existing  forms  of  the  group  in  the  fact  that  the  bodies 
of  the  vertebrae,  like  those  of  the  Jurassic  Crocodiles,  are 
bi-concave,  or  hollowed  out  at  both  ends.  In  the  Greensand 
of  North  America,  however,  occur  the  remains  of  Crocodiles 
which  agree  with  all  the  living  species  in  having  the  bodies  of 
the  vertebrae  in  the  region  of  the  back  hollowed  out  in  front 
and  convex  behind. 

Birds  have  not  hitherto  been  shown,  with  certainty,  to  have 
existed  in  Europe  during  the  Cretaceous  period,  except  in  a 
few  instances  in  which  fragmentary  remains  belonging  to  this 
class  have  been  discovered.  The  Cretaceous  deposits  of 
North  America  have,  however,  been  shown  by  Professor 
Marsh  to  contain  a  considerable  number  of  the  remains  of 
Birds,  often  in  a  state  of  excellent  preservation.  Some  of 
these  belong  to  Swimming  or  Wading  Birds,  differing  in  no 
point  of  special  interest  from  modern  birds  of  similar  habits. 
Others,  however,  exhibit  such  extraordinary  peculiarities  that 
they  merit  more  than  a  passing  notice.  One  of  the  forms  in 
question  constitutes  the  genus  Ichthyornis  of  Marsh,  the  type- 
species  of  which  (/.  dispar)  was  about  as  large  as  a  Pigeon. 
In  two  remarkable  respects,  this  singular  Bird  differs  from  all 
known  living  members  of  the  class.  One  of  these  respects 
concerns  the  jaws,  both  of  which  exhibit  the  Reptilian  char- 
acter of  being  armed  with  numerous  small  pointed  teeth  (fig. 
2  1 2,  a),  sunk  in  distinct  sockets.  No  existing  bird  possesses 
teeth ;  and  this  character  forcibly  recalls  the  Bird-like  Ptero- 
saurs, with  their  toothed  jaws.  Ichthyornis,  however,  possessed 
fore-limbs  constructed  strictly  on  the  type  of  the  "wing"  of  the 
living  Birds;  and  it  cannot,  therefore,  be  separated  from  this 
class.  Another  extraordinary  peculiarity  of  Ichthyornis  is,  that 
the  bodies  of  the  vertebra  (fig.  212,  c)  were  bi-concave,  as  is  the 
case  with  many  extinct  Reptiles  and  almost  all  Fishes,  but  as 
does  not  occur  in  any  living  Bird.  There  can  be  little  doubt 
that  Ichthyornis  was  aquatic  in  its  habits,  and  that  it  lived  prin- 
cipally upon  fishes ;  but  its  powerful  wings  at  the  same  time 
indicate  that  it  was  capable  of  prolonged  flight.  The  tail  of 
Ichthyornis  has,  unfortunately,  not  been  discovered  ;  and  it  is 
at  present  impossible  to  say  whether  this  resembled  the  tail  of 
existing  Birds,  or  whether  it  was  elongated  and  composed  of 
separate  vertebrae,  as  in  the  Jurassic  Archceopteryx. 

Still  more  wonderful  than  Ichthyornis  is  the  marvellous  bird 
described  by  Marsh  under  the  name  of  Hesperornis  regalis. 
This  presents  us  with  a  gigantic  diving  bird,  somewhat  re- 
sembling the  existing  "Loons"  (Colymbus],  but  agreeing 
with  Ichthvornis  in  having  the  jaws  furnished  with  conical, 


282 


HISTORICAL    PALAEONTOLOGY. 


recurved,  pointed  teeth  (fig.  212,  b\  Hence  these  forms  are 
grouped  together  in  a  new  sub-class,  under  the  name  of  Odon- 
tornithes  or  "  Toothed  Birds."  The  teeth  of  Hesperornis  (fig. 
212,  d)  resemble  those  of  Ichthyornis  in  their  general  form; 


Fig.  212. — Toothed  Birds  {Odontoniithes)  of  the  Cretaceous  Rocks  of  America,  a, 
Left  lower  jaw  of  Ichthyornis  dispar,  slightly  enlarged  ;  b,  Left  lower  jaw  of  Hesperornis 
regalis,  reduced  to  nearly  one-fourth  of  the  natural  size ;  c,  Cervical  vertebra  of  Ichthyornis 
dispar,  front  view,  twice  the  natural  size  ;  c1,  Side  view  of  the  same  ;  dt  Tooth  of  Hesper- 
ornis regalis,  enlarged  to  twice  the  natural  size.  (After  Marsh.) 

but  instead  of  being  sunk  in  distinct  sockets,  they  are  simply 
implanted  in  a  deep  continuous  groove  in  the  bony  substance 
of  the  jaw.  The  front  of  the  upper  jaw  does  not  carry  teeth, 
and  was  probably  encased  in  a  horny  beak.  The  breast-bone 
is  entirely  destitute  of  a  central  ridge  or  keel,  and  the  wings 
are  minute  and  quite  rudimentary ;  so  that  Hesperornis^  unlike 
Ichthyornis,  must  have  been  wholly  deprived  of  the  power  of 
flight,  in  this  respect  approaching  the  existing  Penguins.  The 
tail  consists  of  about  twelve  vertebrae,  of  which  the  last  three  or 
four  are  amalgamated  to  form  a  flat  terminal  mass,  there  being 
at  the  same  time  clear  indications  that  the  tail  was  capable 
of  up  and  down  movement  in  a  vertical  plane,  this  proba- 
bly fitting  it  to  serve  as  a  swimming-paddle  or  rudder.  The 
legs  were  powerfully  constructed,  and  the  feet  were  adapted  to 
assist  the  bird  in  rapid  motion  through  the  water.  The  known 
remains  ^Hesperornis  regalis  prove  it  to  have  been  a  swim- 
ming and  diving  bird,  of  larger  dimensions  than  any  of  the 


THE   CRETACEOUS   PERIOD.  283 

aquatic  members  of  the  class  of  Birds  with  which  we  are  ac- 
quainted at  the  present  day.  It  appears  to  have  stood  between 
five  and  six  feet  high,  and  its  inability  to  fly  is  fully  compen- 
sated for  by  the  numerous  adaptations  of  its  structure  to  a 
watery  life.  Its  teeth  prove  it  to  have  been  carnivorous  in  its 
habits,  and  it  probably  lived  upon  fishes.  It  is  a  curious  fact 
that  two  Birds  agreeing  with  one  another  in  the  wholly  abnor- 
mal character  of  possessing  teeth,  and  in  other  respects  so 
entirely  different,  should,  like  Ichtliyornis  and  Hesperornis, 
have  lived  not  only  in  the  same  geological  period,  but  also  in 
the  same  geographical  area ;  and  it  is  equally  curious  that 
the  area  inhabited  by  these  toothed  Birds  should  at  the  same 
time  have  been  tenanted  by  winged  and  bird-like  Reptiles 
belonging  to  the  toothed  genus  Pterodactylus  and  the  toothless 
genus  Pteranodon. 

No  remains  of  Mammals,  finally,  have  as  yet  been  detected 
in  any  sedimentary  accumulations  of  Cretaceous  age. 


LITERATURE. 

The  following  list  comprises  some  of  the  more  important  works  and 
memoirs  which  may  be  consulted  with  reference  to  the  Cretaceous  strata 
and  their  fossil  contents  : — 

(1)  '  Memoirs  of  the  Geological  Survey  of  Great  Britain.' 

(2)  'Geology  of  England  arid  Wales.'     Conybeare  and  Phillips. 

(3)  '  Geology  of  Yorkshire,' vol.  ii.     Phillips. 

(4)  'Geology  of  Oxford  and  the  Thames  Valley.'     Phillips. 

(5)  '  Geological  Excursions  through  the  Isle  of  Wight.'     Mantell. 

(6)  '  Geology  of  Sussex.'     Mantell. 

(7)  '  Report  on  Londonderry,'  &c.     Portlock. 

(8)  'Recherches  sur  le  Terrain  Cretace  Superieur  de  1* Angle terre  et  de 

1'Irlande.'     Barrpis. 

(9)  "  Geological  Survey  of  Canada  " — '  Report  of  Progress,  1872-73.' 
(10)   '  Geological  Survey  of  California.'     Whitney. 

(n)  'Geological   Survey   of   Montana,   Idaho,    Wyoming,    and    Utah.' 
Hayden  and  Meek. 

(12)  'Report   on    Geology,'   &c.    (British    North    American    Boundary 

Commission).      G.  M.  Dawson. 

(13)  'Manual  of  Geology.'     Dana. 

(14)  '  Lethsea  Rossica. '     Eichwald. 

(15)  '  Petrefacta  Germanise.'     Goldfuss. 

(16)  'Fossils  of  the  South  Downs.'     Mantell. 

(17)  'Medals,  of  Creation.'     Mantell. 

(18)  '  Mineral  Conchology.'     Sowerby. 

(19)  '  Lethaea  Geognostica.'     Bronn. 

(20)  ' Malacostracous  Crustacea  of  the   British  Cretaceous   Formation' 


(Palaeontographical  Society).     Bell. 
Brachiopoda  of    t 


(21)  'Brachiopoda  of    the   Cretaceous    Formation'    (Palaeontographical 

Society).     Davidson. 

(22)  'Corals  of  the  Cretaceous  Formation'  (Paleeontographical  Society). 

Mi 'ne-Edwards  and  Haime. 


284  HISTORICAL   PALAEONTOLOGY. 

(23)  '  Supplement  to  the   Fossil    Corals '    (Palaeontographical   Society). 

Martin  Duncan. 

(24)  ' Echinodermata  of  the  Cretaceous  Formation'  (Palseontographical 

Society).     Wright. 

(25)  'Monograph    of    the    Belemnitidae '    (Palaeontographical    Society). 

Phillips. 

(26)  'Monograph     of     the     Trigoniae '     (Palaeontographical      Society). 

Lycett. 

(27)  '  Fossil  Cirripedes  '  (Pabeontographical  Society).     Darwin. 

(28)  '  Fossil    Mollusca   of    the   Chalk   of    Britain  '    (Palaeontographical 

Society).     Sharpe. 

(29)  '  Entomostraca  of  the  Cretaceous  Formation'     (Palaeontographical 

Society).     Rupert  Jones. 

(30)  '  Monograph  of  the  Fossil  Reptiles  of  the  Cretaceous  Formation ' 

(Palaeontographical  Society).     Owen. 

(31)  '  Manual  of  Palaeontology.'     Owen. 

(32)  '  Synopsis  of  Extinct  Batrachia  and  Reptilia.'     Cope. 

(33)  "Structure  of  the  Skull  and  Limbs  in  Mosasauroid  Reptiles  "- 

'  American  Journ.  Sci.  and  Arts,  1872.'     Marsh. 

(34)  "On    Odontornithes " — 'American  Journ.   Sci.  and   Arts,    1875.' 

Marsh. 

(35)  'Ossemens  Fossiles.'     Cuvier. 

(36)  'Catalogue  of  Ornithosauria.'     Seeley. 

(37)  '  Paleontologie  Francaise. '     D'Orbigny. 

(38)  'Synopsis  des  Echinides  fossiles.'     Desor. 

(39)  'Cat.  Raisonne  des  Echinides.'     Agassiz  and  Desor. 

(40)  ' '  Echinoids  " — '  Decades  of  the  Geol.  Survey  of  Britain. '    E.  Forbes. 

(41)  '  Paleontologie  Francaise.'     Cotteau. 

(42)  '  Versteinerungen  der  Bohmischen  Kreide-formation.'     Reuss. 

(43)  "Cephalopoda,  Gasteropoda,  Pelecypoda,  Brachiopoda,  &c.,  of  the 

Cretaceous  Rocks  of  India" — '  Palseontologica  Indica,'  ser.   i., 
iii.,  v.,  vi.,  viii.      Stoliczka.  . 

(44)  "Cretaceous  Reptiles  of  the  United  States" — 'Smithsonian  Contri- 

butions to  Knowledge,'  vol.  xiv.     Leidy. 

(45)  '  Invertebrate  Cretaceous,  and  Tertiary  Fossils  of  the  Upper  Mis- 

souri Country.'     1876.     Meek. 


CHAPTER    XVIII. 
THE    EOCENE   PERIOD. 

Before  commencing  the  study  of  the  subdivisions  of  the 
Kainozoic  series,  there  are  some  general  considerations  to  be 
noted.  In  the  first  place,  there  is  in  the  Old  World  a  com- 
plete and  entire  physical  break  between  the  rocks  of  the 
Mesozoic  and  Kainozoic  periods.  In  no  instance  in  Europe 
are  Tertiary  strata  to  be  found  resting  conformably  upon  any 
Secondary  rock.  The  Chalk  has  invariably  suffered  much 
erosion  and  denudation  before  the  lowest  Tertiary  strata  were 
deposited  upon  it.  This  is  shown  by  the  fact  that  the  actually 


THE   EOCENE    PERIOD.  285 

eroded  surface  of  the  Chalk  can  often  be  seen  ;  or,  failing  this, 
that  we  can  point  to  the  presence  of  the  chalk-flints  in  the 
Tertiary  strata.  This  last,  of  course,  affords  unquestionable 
proof  that  the  Chalk  must  have  been  subjected  to  enormous 
denudation  prior  to  the  formation  of  the  Tertiary  beds,  all  the 
chalk  itself  having  been  removed,  and  nothing  left  but  the 
flints,  while  these  are  all  rolled  and  rounded.  In  the  continent 
of  North  America,  on  the  other  hand,  the  lowest  Tertiary  strata 
have  been  shown  to  graduate  downwards  conformably  with  the 
highest  Cretaceous  beds,  it  being  a  matter  of  difficulty  to  draw 
a  precise  line  of  demarcation  between  the  two  formations. 

In  the  second  place,  there  is  a  marked  break  in  the  life  of 
the  Mesozoic  and  Kainozoic  periods.  With  the  exception  of 
a  few  Foraminifera,  and  one  Brachiopod  (the  latter  doubtful), 
no  Cretaceous  species  is  known  to  have  survived  the  Creta- 
ceous period;  while  several  characteristic  families,  such  as  the 
Ammonitidcz,  Belemnitidcz,  and  Hippuritid&i  died  out  entirely 
with  the  close  of  the  Cretaceous  rocks.  In  the  Tertiary  rocks, 
on  the  other  hand,  not  only  are  all  the  animals  and  plants 
more  or  less  like  existing  types,  but  we  meet  with  a  constantly- 
increasing  number  of  living  species  as  we  pass  from  the  bottom 
of  the  Kainozoic  series  to  the  top.  Upon  tin's  last  fact  is 
founded  the  modern  classification  of  the  Kainozoic  rocks, 
propounded  by  Sir  Charles  Lyell. 

The  absence  in  strata  of  Tertiary  age  of  the  chambered 
Cephalopods,  the  Belemnites,  the  Hippuritcs,  the  Inocerami, 
and  the  diversified  types  of  Reptiles  which  form  such  con- 
spicuous features  in  the  Cretaceous  fauna,  render  the  palaeon- 
tological  break  between  the  Chalk  and  the  Eocene  one  far  too 
serious  to  be  overlooked.  At  the  same  time,  it  is  to  be  re- 
membered that  the  evidence  afforded  by  the  explorations  car- 
ried out  of  late  years  as  to  the  animal  life  of  the  deep  sea,  ren- 
ders it  certain  that  the  extinction  of  marine  forms  of  life  at  the 
close  of  the  Cretaceous  period  was  far  less  extensive  than  had 
been  previously  assumed.  It  is  tolerably  certain,  in  fact,  that 
we  may  look  upon  some  of  the  inhabitants  of  the  depths  of  our 
existing  oceans  as  the  direct,  if  modified,  descendants  of  ani- 
malsxwhich  were  in  existence  when  the  Chalk  was  deposited. 

It  follows  from  the  general  want  of  conformity  between  the 
Cretaceous  and  Tertiary  rocks,  and  still  more  from  the  great 
difference  in  life,  that  the  Cretaceous  and  Tertiary  periods. are 
separated,  in  the  Old  World  at  any  rate,  by  an  enormous  lapse 
of  unrepresented  time.  How  long  this  interval  may  have  been, 
we  have  no  means  of  judging  exactly,  but  it  very  possibly  was 
as  long  as  the  whole  Kainozoic  epoch,  itself.  Seme  day  we 
20 


286  HISTORICAL   PALEONTOLOGY. 

shall  doubtless  find,  at  some  part  of  the  earth's  surface,  marine 
strata  which  were  deposited  during  this  period,  and  which  will 
contain  fossils  intermediate  in  character  between  the  organic, 
remains  which  respectively  characterise  the  Secondary  and 
Tertiary  periods.  At  present,  we  have  only  slight  traces  of 
such  deposits — as,  for  instance,  the  Maestricht  beds,  the  Faxoe 
Limestone,  and  the  Pisolitic  Limestone  of  France. 

CLASSIFICATION  OF  THE  TERTIARY  ROCKS. — The  classifica- 
tion of  the  Tertiary  rocks  is  a  matter  of  unusual  difficulty,  in 
consequence  of  their  occurring  in  disconnected  basins,  form- 
ing a  series  of  detached  areas,  which  hold  no  relations  of 
superposition  to  one  another.  The  order,  therefore,  of  the 
Tertiaries  in  point  of  time,  can  only  be  determined  by  an  ap- 
peal to  fossils ;  and  in  such  determination  Sir  Charles  Lyell 
proposed  to  take  as  the  basis  of  classification  the  proportion  of 
living  or  existing  species  of  Mollusca  which  occurs  in  each  stratum 
or  group  of  strata.  Acting  upon  this  principle,  Sir  Charles 
Lyell  divides  the  Tertiary  series  into  four  groups  : — 

I.  The  Eocene  formation  (Or.  eos,  dawn  ;  kainos,  new),  con- 
taining the  smallest  proportion  of  existing  species,  and  being, 
therefore,  the  oldest  division.     In  this  classification,  only  the 
Mollusca  are  taken  into  account ;  and  it  was  found  that  of 
these  about  three  and  a  half  per  cent  were  identical  with  ex- 
isting species. 

II.  The  Miocene  formation  (Gr.  melon,  less;  kainos,  new), 
with  more  recent  species  than  the  Eocene,  but  less  than  the  suc- 
ceeding formation,  and  less  than  one-half  the  total  number  in  the 
formation.    As  before,  only  the  Mollusca  are  taken  into  account, 
and  about  17  per  cent  of  these  agree  with  existing  species. 

III.  The  Pliocene  formation  (Gr.  pleion,  more;  kainos,  new), 
with  generally  more  than  half  the  species  of  shells  identical  with 
existing  species — the  proportion  of  these  varying  from  35  to 
50  per  cent  in  the  lower  beds  of  this  division,  up  to  90  or  95 
per  cent  in  its  higher  portion. 

IV.  The  Post- Tertiary  Formations,  in  which  all  the  shells 
belong  to  existing  species.     This,  in  turn,  is  divided  into  two 
minor  groups — the  Post-Pliocene  and  Recent  Formations.     In 
the  Post-Pliocene  formations,  while  all  the  Mollusca  belong  to 
existing   species,    most   of  the   Mammals   belong   to    extinct 
species.     In  the  Recent  period,  the  quadrupeds,  as  well  as  the 
shells,  belong  to  living  species. 

The  above,  with  some  modifications,  was  the  original  classi- 
fication proposed  by  Sir  Charles  Lyell  for  the  Tertiary  rocks, 
and  now  universally  accepted.  More  recent  researches,  it  is 
true,  have  somewhat  altered  the  proportions  of  existing  species 


THE   EOCENE   PERIOD.  287 

to  extinct,  as  stated  above.  The  general  principle,  however, 
of  an  increase  in  the  number  of  living  species,  still  holds  good  ; 
and  this  is  as  yet  the  only  satisfactory  basis  upon  which  it  has 
been  proposed  to  arrange  the  Tertiary  deposits. 

EOCENE  FORMATION. 

The  Eocene  rocks  are  the  lowest  of  the  Tertiary  series,  and 
comprise  all  those  Tertiary  deposits  in  which  there  is  only  a 
small  proportion  of  existing  Mollnsca — from  three  and  a  half 
to  five  per  cent.  The  Eocene  rocks  occur  in  several  basins  in 
Britain,  France,  the  Netherlands,  and  other  parts  of  Europe, 
and  in  the  United  States.  The  subdivisions  which  have  been 
established  are  extremely  numerous,  and  it  is  often  impossible 
to  parallel  those  of  one  basin  with  those  of  another.  It  will 
be  sufficient,  therefore,  to  accept  the  division  of  the  Eocene 
formation  into  three  great  groups — Lower,  Middle,  and  Upper 
Eocene — and  to  consider  some  of  the  more  important  beds 
comprised  under  these  heads  in  Europe  and  in  North  America. 

I.  EOCENE  OF  BRITAIN,  (i.)  LOWER  EOCENE. — The  base 
of  the  Eocene  series  in  Britain  is  constituted  by  about  90  feet 
of  light-coloured,  sometimes  argillaceous  sands  (Thanet  Sands), 
which  are  of  marine  origin.  Above  these,  or  forming  the  base 
of  the  formation  where  these  are  wanting,-  come  mottled  clays 
and  sands  with  lignite  ( Woolwich  and  .Reading  series),  which 
are  estuarine  or  fluvio-marine  in  origin.  The  highest  member 
of  the  Lower  Eocene  of  Britain  is  the  "London  Clay"  consist- 
ing of  a  great  mass  of  dark-brown  or  blue  clay,  sometimes  with 
sandy  beds,  or  with  layers  of  "  septaria,"  the  whole  attaining  a 
thickness  of  from  200  to  as  much  as' 500  feet.  The  London 
Clay  is  a  purely  marine  deposit,  containing  many  marine  fossils, 
with  the  remains  of  terrestrial  animals  and  plants  ;  all  of  which 
indicate  a  high  temperature  of  the  sea  and  tropical  or  sub- 
tropical conditions  of  the  land. 

(2.)  MIDDLE  EOCENE. — The  inferior  portion  of  the  Middle 
Eocene  of  Britain  consists  of  marine  beds,  chiefly  consisting 
of  sand,  clays,  and  gravels,  and  attaining  a  very  considerable 
thickness  (Bagshot  and  Bracklesham  beds).  The  superior  por- 
tion of  the  Middle  Eocene  of  Britain,  on  the  other  hand,  con- 
sists of  deposits  which  are  almost  exclusively  fresh-water,  or 
brackish-water  in  origin  {Ifeadon  and  Osborne  series). 

The  chief  Continental  formations  of  Middle  Eocene  age  are 
the  "  Calcaire  grossier"  of  the  Paris  basin,  and  the  "Num- 
mulitic  Limestone  "  of  the  Alps. 

(3.)  UPPER  EOCENE.— If  the  Headon  and  Osborne  beds  of 


288  HISTORICAL   PALEONTOLOGY. 

the  Isle  of  Wight  be  placed  in  the  Middle  Eocene,  the  only 
British  representatives  of  the  Upper  Eocene  are  the  Bembridge 
beds.  These  strata  consist  of  limestones,  clays,  and  marls, 
which  have  for  the  most  part  been  deposited  in  fresh  or  brack- 
ish water. 

II.  EOCENE    BEDS   OF  THE  PARIS  BASIN.  —  The    Eocene 
strata  are  very  well  developed  in  the  neighbourhood  of  Paris, 
where  they  occupy  a  large  area  or  basin  scooped  out  of  the 
Chalk.     The  beds  of  this  area  are  partly  marine,  partly  fresh- 
water in  origin ;    and   the  following   table  (after  Sir  Charles 
Lyell)  shows  their  subdivisions  and  their  parallelism  with  the 
English  series  : — 

GENERAL  TABLE  OF  FRENCH  EOCENE  STRATA. 
UPPER  EOCENE. 

French  Subdivisions.  English  Equivalents. 

A.    I.  Gypseous   series   of    Mont-          I.   Bembridge  series. 

martre. 
A.   2.   Calcaire   silicieux,    or   Tra-          2.   Osborne  and  Headon  series. 

vertin  Inferieur. 

A.  3.   Gres     de     Beauchamp,     or         3.   White  sand  and  clay  of  Barton 

Sables  Moyens.  Cliff,  Hants. 

MIDDLE    EOCENE. 

B.  I.   Calcaire  Grossier.  i.   Bagshot  and  Bracklesham  beds. 

B.  2.   Soissonnais   Sands,   or  Lits          2.   Wanting. 

Coquiliievs. 

LOWER    EOCENE. 

C.  I.   Argilede  Londres  at  base  of          i.   London  clay. 

Hill  of  Cassel,  near  Dun- 
kirk. 

C.   2.   Argile  plastique  and  lignite.          2.   Plastic  clay  and  sand  with  lig- 
nite (Woolwich  and  Reading 
series). 
C.   3.   Sables  de  Braclieux.  3    Thanet  sands. 

III.  EOCENE  STRATA  OF  THE  UNITED  STATES. — The  low- 
est member  of  the  Eocene  deposits  of  North  America  is  the 
so-called  "  Lignitic  Formation"  which  is  largely  developed  in 
Mississippi,  Tennessee,  Arkansas,  Wyoming,  Utah,  Colorado, 
and  California,  and  sometimes  attains  a  thickness  of  several 
thousand  feet.     Stratigraphically,  this  formation    exhibits   the 
interesting  point  that  it  graduates  downwards  insensibly  and 
conformably  into  the  Cretaceous,  whilst  it  is  succeeded  uncon- 

formably  by  strata  of  Middle  Eocene  age.  Lithologically,  the 
series  consists  principally  of  sands  and  clays,  with  beds  of  lig- 
nite and  coal,  and  its  organic  remains  show  that  it  is  principally 
of  fresh-water  origin  with  a  partial  intermixture  of  marine  beds. 


THE   EOCENE   PERIOD.  289 

These  marine  strata  of  the  "  Lignitic  formation  "  are  of  special 
interest,  as  showing  such  a  commingling  of  Cretaceous  and 
Tertiary  types  of  life,  that  it  is  impossible  to  draw  any  rigid 
line  in  this  region  between  the  Mesozoic  and  Kainozoic  sys- 
tems. Thus  the  marine  beds  of  the  Lignitic  series  contain 
such  characteristic  Cretaceous  forms  as  Inoceramus  and  Am- 
monites, along  with  a  great  number  of  Univalves  of  a  distinctly 
Tertiary  type  (Cones,  Cowries,  &c.)  Upon  the  whole,  there- 
fore, we  must  regard  this  series  of  deposits  as  affording  a  kind 
of  transition  between  the  Cretaceous  and  the  Eocene,  holding 
in  some  respects  a  position  which  may  be  compared  with  that 
held  by  the  Purbeck  beds  in  Britain  as  regards  the  Jurassic 
and  Cretaceous. 

The  Middle  Eocene  of  the  United  States  is  represented 
by  the  Claiborne  and  Jackson  beds.  The  Claiborne  series  is 
extensively  developed  at  Claiborne,  Alabama,  and  consists  of 
sands,  clays,  lignites,  marls,  and  impure  limestones,  containing 
marine  fossils  along  with  numerous  plant-remains.  The  Jack- 
son series  is  represented  by  lignitic  clays  and  marls  which  occur 
at  Jackson,  Mississippi.  Amongst  the  more  remarkable  fossils 
of  this  series  are  the  teeth  and  bones  of  Cetaceans  of  the 
genus  Zcitglodon. 

Strata  of  Upper  Eocene  age  occur  in  North  America  t,t 
Vicksburg,  Mississippi,  and  are  known  as  the  Vicksbtirg  series. 
They  consist  of  lignites,  clays,  marls,  and  limestones.  Fresh- 
water deposits  of  Eocene  age  are  also  largely  developed  in 
parts  of  the  Rocky  Mountain  region.  The  most  remarkable 
fossils  of  these  beds  are  Mammals,  of  which  a  large  number  of 
species  have  been  already  determined. 

LIFE  OF  THE  EOCENE  PERIOD. 

The  fossils  of  the  Eocene  deposits  are  so  numerous  that 
nothing  more  can  be  attempted  here  than  to  give  a  brief  and 
general  sketch  of  the  life  of  the  period,  special  attention  being 
directed  to  some  of  the  more  prominent  and  interesting  types, 
amongst  which — as  throughout  the  Tertiary  series — the  Mam- 
mals hold  the  first  place.  It  is  not  uncommon,  indeed,  to 
speak  of  the  Tertiary  period  as  a  whole  under  the  name  of  the 
"  Age  of  Mammals,"  a  title  at  least  as  well  deserved  as  that  of 
"  Age  of  Reptiles  "  applied  to  the  Mesozoic,  or  "  Age  of  Mol- 
luscs "  applied  to  the  Palaeozoic  epoch. 

As  regards  foe  plants  of  the  Eocene,  the  chief  point  to  be 
noticed  is,  that  the  conditions  which  had  already  set  in  with 
the  commencement  of  the  Upper  Cretaceous,  are  here  con- 


2QO  HISTORICAL  PALAEONTOLOGY. 

tinued,  and  still  further  enforced.  The  Cycads  of  the  Secondary 
period,  if  they  have  not  totally  disappeared,  are  exceedingly 
rare ;  and  the  Conifers,  losing  the  predominance  which  they 
enjoyed  in  the  Mesozoic,  are  now  relegated  to  a  subordinate 
though  well-defined  place  in  the  terrestrial  vegetation.  The 
great  majority  of  the  Eocene  plants  are  referable  to  the  groups 
of  the  Angiospermous  Exogens  and  the  Monocotyledons  ;  and 
the  vegetation  of  the  period,  upon  the  whole,  approximates 
closely  to  that  now  existing  upon  the  earth.  The  plants  of  the 
European  Eocene  are,  however,  in  the  main  most  closely  allied 
to  forms  which  are  now  characteristic  of  tropical  or  sub-tropical 
regions.  Thus,  in  the  London  Clay  are  found  numerous  fruits 
of  Palms  (Nipadites,  fig.  213),  along  with  various  other  plants, 
most  of  which  indicate  a  warm  climate 
as  prevailing  in  the  south  of  England 
at  the  commencement  of  the  Eocene 
period.  •  In  the  Eocene  strata  of  North 
America  occur  numerous  plants  belong- 
ing to  existing  types — such  as  Palms, 
Conifers,  the  Magnolia,  Cinnamon,  Fig, 
Dog-wood,  Maple,  Hickory,  Poplar, 
Plane,  £c.  Taken  as  a  whole,  the 
Eocene  flora  of  North  America  is  nearly 
related  to  that  of  the  Miocene  strata  of 
Europe,  as  well  as  to  that  now  existing 
»  the  American  area.  We  may  con- 
London  day,  isle  of  Sheppey.  elude,  therefore,  that  "the  forests  or 
the  American  Eocene  resembled  those 

of  the  European  Miocene,   and  even    of  modern  America " 
(Dana). 

As  regards  the  animals  of  the  Eocene  period,  the  Protozoans 
are  represented  by  numerous  Foraminifera,  which  reach  here 
their  maximum  of  development,  both  as  regards  the  size  of 
individuals  and  the  number  of  generic  types.  Many  of  the 
Eocene  Foraminifers  are  of  small  size ;  but  even  these  not 
uncommonly  form  whole  rock-masses.  Thus,  the  so-called 
"  Miliolite  Limestone "  of  the  Paris  basin,  largely  used  as  a 
building  stone,  is  almost  wholly  composed  of  the  shells  of  a 
small  species  of  Miliola.  The  most  remarkable,  however,  of 
the  many  members  of  this  group  of  animals  which  flourished  in 
Eocene  times,  are  the  "  Nummulites  "  (Nummulina}^  so  called 
from  their  resemblance  in  shape  to  coins  (Lat.  minimus^  a  coin). 
The  Nummulites  are  amongst  the  largest  of  all  known  Fora- 
minifera,  sometimes  attaining  a  size  of  three  inches  in  circum- 
ference ;  and  their  internal  structure  is  very  complex  (fig.  214). 


THE   EOCENE   PERIOD. 


291 


Many  species  are  known,  and  they  are  particularly  character- 
istic of  the  Middle  and  Upper  of  these  periods — their  place 


Fig.  214. — Nnmmulina  Icevigata.     Middle  Eocene. 


being  sometimes  taken  by  Orbitoides,  a  form  very  similar  to  the 
Nummulite  in  external  appearance,  but  differing  in  its  internal 
details.  In  the  Middle  Eocene,  the  remains  of  Nummulites 
are  found  in  vast  numbers  in  a  very  widely-spread  and  easily- 
recognised  formation  known  as  the  "Nummulitic  Limestone" 
(fig.  10).  According  to  Sir  Charles  Lyell,  "the  Nummulitic 
Limestone  of  the  Swiss  Alps  rises  to  more  than  10,000  feet 
above  the  level  of  the  sea,  and  attains  here  and  in  other  moun- 
tain-chains a  thickness  of  several  thousand  feet.  It  may  be 
said  to  play  a  far  more  conspicuous  part  than  any  other  Tertiary 
group  in  the  solid  framework  of  the  earth's  crust,  whether  in 
Europe,  Asia,  or  Africa.  It  occurs  in  Algeria  and  Morocco, 
and  has  been  traced  from  Egypt,  where  it  was  largely  quarried 
of  old  for  the  building  of  the  Pyramids,  into  Asia  Minor,  and 
across  Persia  by  Bagdad  to  the  mouths  of  the  Indus.  It  has 
been  observed  not  only  in  Cutch,  but  in  the  mountain-ranges 
which  separate  Scinde  from  Persia,  and  which  form  the  passes 
leading  to  Cabul ;  and  it  has  been  followed  still  further  east- 
ward into  India,  as  far  as  Eastern  Bengal  and  the  frontiers  of 
China."  The  shells  of  Nummulites  have  been  found  at  an 
elevation  of  16,500  feet  above  the  level  of  the  sea  in  Western 
Thibet ;  and  the  distinguished  and  philosophical  geologist  just 
quoted,  further  remarks,  that  "when  we  have  once  arrived  at 
the  conviction  that  the  Nummulitic  formation  occupies  a  mid- 
dle and  upper  place  in  the  Eocene  series,  we  are  struck  with 
the  comparatively  modern  date  to  which  some  of  the  greatest 
revolutions  in  the  physical  geography  of  Europe,  Asia,  and 
Northern  Africa  must  be  referred.  All  the  mountain-chains — 
such  as  the  Alps,  Pyrenees,  Carpathians,  and  Himalayas — into 
the  composition  of  whose  central  and  loftiest  parts  the  Num- 
mulitic strata  enter  bodily,  could  have  had  no  existence  till 


292 


HISTORICAL   PALAEONTOLOGY. 


after  the  Middle  Eocene  period.  During  that  period,  the  sea 
prevailed  where  these  chains  now  rise ;  for  Nummulites  and 
their  accompanying  Testacea  were  unquestionably  inhabitants 
of  salt  water." 

The  Ccelenterates  of  the  Eocene  are  represented  principally 
by  Corals,  mostly  of  types  identical  with  or  nearly  allied  to 
those  now  in  existence.  Perhaps  the  most  characteristic  group 
of  these  is  that  of  the  TurbinoUda,  comprising  a  number  of 
simple  u  cup  corals,"  which  probably  lived  in  moderately  deep 
water.  One  of  the  forms  belonging  to  this  family  is  here 
figured  (fig.  215).  Besides  true  Corals,  the  Eocene  deposits 
have  yielded  the  remains  of  the  "  Sea- 
pens  "  (Pennatulida)  and  the  branched 
skeletons  of  the  "Sea-shrubs"  (Gorgonidcz). 
The  Echinodertns  are  represented  prin- 
cipally by  Sea-urchins,  and  demand  nothing 
more  than  mention.  It  is  to  be  observed, 
however,  that  the  great  group  of  the  Sea- 
lilies  (Crinoids)  is  now  verging  on  extinc- 
tion, and  is  but  very  feebly  represented. 

Amongst  the Mollusca^e,  Polyzoans  and 
Brachiopods  also  require  no  special  men- 
tion, beyond  the  fact  that  the  latter  are 
greatly  reduced  in  numbers,  and  belong 
principally  to  the  existing  genera  Terc- 
bratula  and  Rhynchcndla.  The  Bivalves 
(Lamdlibranchs]  and  the  Univalves  (Ga:~ 
teropods]  are  exceedingly  numerous,  and 
almost  all  the  principal  existing  genera  are 
now  represented ;  though  less  than  five 
per  cent  of  the  Eocene  species  are  identical 
with  those  now  living.  It  is  difficult  to 
make  any  selection  from  the  many  Bivalves 
which  are  known  in  deposits  of  this  age ; 
but  species  of  Cardita,  Crassatella,  Leda, 
Cyrena,  Mactra,  Cardinm,  Psammobia,&.c.., 
may  be  mentioned  as  very  characteristic. 
The  Cardita  planicosta  here  figured  (fig. 
216)  is  not  only  very  abundant  in  the 
Middle  Eocene,  but  is  very  widely  distri- 
buted, ranging  from  Europe  to  the  Pacific  coast  of  North 
America.  The  Univalves  of  the  Eocene  are  extremely  nu- 
merous, and  generally  beautifully  preserved.  The  majority 
of  them  belong  to  that  great  section  of  the  Gasteropods  in 
which  the  mouth  of  the  shell  is  notched  or  produced  into 


Fig.  215.  —  Turbinolin 
siilcata,  viewed  from  one 
side,  and  from  above. 
Eocene. 


THE   EOCENE    PERIOD. 


293 


a  canal  (when  the  shell  is  said  to  be  "  siphonostomatous  ") — - 
this    section    including   the  carnivorous  and  most   highly- or- 


Fig.  216.— Cardlta  planicosta.     Middle  Eocene. 

gani3ed  groups  of  the  class.  Not  only  is  this  the  case,  but 
a  large  number  of  the  Eocene  Univalves  belong  to  types 
which  now  attain  their  maximum  of  development  in  the 
warmer  regions  of  the  globe.  Thus  we  find  numerous  species 
of  Cones  (Comis),  Volutes  ( Valuta},  Cowries  (Cyprcza,  fig.  218), 


Fi£.  217. — Typhis  titb;fer,  a  "siphonosto- 
matous "  Univalve.     Eocene. 


Fig.  218.  —  Cy/>ra-a 
elegans.    Eocene. 


Olives  and  Rice-shells  (Ofiva),  Mitre-shells  (Mitra\  Trumpet- 
shells  (Triton),  Auger-shells  (Terebra),  and  Fig-shells  (Pyrula). 
Along  with  these  are  many  forms  of  Plcurotoma,  Itostdlaria, 
Spindle-shells  (Fusus),  Dog-whelks  (Nassa\  Murices,  and  many 
round-mouthed  ("  holostomatous  ")  species,  belonging  to  such 
genera  as  Turritdla,  Ncrita,  Natica,  Scalaria,  &c.  Hie  genus 
Cerithium  (fig.  219),  most  of  the  living  forms  of  which  are 
found  in  warm  regions,  inhabiting  fresh  or  brackish  waters, 
undergoes  a  vast  development  in  the  Eocene  period,  where  it 


294 


HISTORICAL   PALEONTOLOGY. 


is  represented  by  an  immense  number  of  specific  forms,  some 
of  which  attain  very  large  dimensions.  In  the  Eocene  strata 
of  the  Paris  basin  alone,  nearly  one  hundred 
and  fifty  species  of  this  genus  have  been 
detected.  The  more  strictly  fresh  -  water 
deposits  of  the  Eocene  period  have  also 
yielded  numerous  remains  of  Univalves  such 
as  are  now  proper  to  rivers  and  lakes,  to- 
gether with  the  shells  of  true  Land-snails. 
Amongst  these  may  be  mentioned  numerous 
species  of  Limneea  (fig.  220), Physa  (fig.  221), 
Melania,  Paludina,  Planorbis,  Helix,  Buli- 
mus,  and  Cydostoma  (fig.  222). 

With  regard  to  the  CepJialopods,  the  chief 
point  to  be  noticed  is,  that  all  the  beautiful 
and  complex  forms  which  peculiarly  char- 
acterised the  Cretaceous  period  have  here 
disappeared.  We  no  longer  meet  with  a 
single  example  of  the  Turrilite,  the  Baculite, 
the  Hamite,  the  Scaphite,  or  the  Ammonite.  The  only  ex- 
ception to  this  statement  is  the  occurrence  of  one  species 


Fig.  zig.—Ceritki- 
iirtt  hexagonum.  Eo- 
cene. 


Fig.    220. — Limneea 
pyramidalis.     Eocene. 


Fig.  221.—  Physa 
columnaris.    Eocene. 


Fig.  222. — Cydostoma 
A  rnoitdii.     Eocene. 


of  Ammonite  in  the  so-called  "  Lignitic  Formation  "  of  North 
America  ;  but  the  beds  containing  this  may  possibly  be  rather 
referable  to  the  Cretaceous  —  and  this  exception  does  not 
affect  the  fact  that  the  Ammonitida,  as  a  family,  had  be- 
come extinct  before  the  Eocene  strata  were  deposited.  The 
ancient  genus  Nautilus  still  survives,  the  sole  representative  of 
the  once  mighty  order  of  the  Tetrabranchiate  Cephalopods. 
In  the  order  of  the  Dibranchiates,  we  have  a  like  phenomenon 
to  observe  in  the  total  extinction  of  the  great  family  of  the 
"  Belemnites."  No  form  referable  to  this  group  has  hitherto 


THE  EOCENE   PERIOD.  295 

been  found  in  any  Tertiary  stratum;  but  the  internal  skeletons 
of  Cuttle-fishes  (such  as  Belosepia)  are  not  unknown. 

Remains  of  Fishes  are  very  abundant  in  strata  of  Eocene 
age,  especially  in  certain  localities.  The  most  famous  depot 
for  the  fossil  fishes  of  this  period  is  the  limestone  of  Monte 
Bolca,  near  Verona,  which  is  interstratified  with  beds  of  vol- 
canic ashes,  the  whole  being  referable  to  the  Middle  Eocene. 
The  fishes  here  seem  to  have  been  suddenly  destroyed  by  a 
volcanic  eruption,  and  are  found  in  vast  numbers.  Agassiz 
has  described  over  one  hundred  and  thirty  species  of  Fishes 
from  this  locality,  belonging  to  seventy-seven  genera.  All 
the  species  are  extinct ;  but  about  one-half  of  the  genera  are 
represented  by  living  forms.  The  great  majority  of  the 


Fig.  223. — Rhombus  minimus,  a  small  fossil  Turbot  from  the  Eocene  Tertiary, 
Monte  Bolca. 

Eocene  Fishes  belong  to  the  order  of  the  "Bony  Fishes" 
(Te/eosfeans),  so  that  in  the  main  the  forms  of  Fishes  charac- 
terising the  Eocene  are  similar  to  those  which  predominate 
in  existing  seas.  In  addition  to  the  above,  a  few  Ganoids  and 
a  large  number  of  Placoids  are  known  to  occur  in  the  Eocene 
rocks.  Amongst  the  latter  are  found  numerous  teeth  of  true 
Sharks,  such  as  Otodus  (fig.  224)  and  Carcharodon.  The 
pointed  and  serrated  teeth  of  the  latter  sometimes  attain  a 
length  of  over  half  a  foot,  indicating  that  these  predaceous 
fishes  attained  gigantic  dimensions ;  and  it  is  interesting  to 
note  that  teeth,  in  external  appearance  very  similar  to  those 
of  the  early  Tertiary  genus  Carcharodon,  have  been  dredged 
from  great  depths  during  the  recent  expedition  of  the  Chal- 
lenger. There  also  occur  not  uncommonly  the  flattened 


296  HISTORICAL   PALAEONTOLOGY. 

teeth  of  Rays  (fig.  225),  consisting  of  flat  bony  pieces  placed 
close  together,  and  forming  "  a  kind  of  mosaic  pavement  on 
both  the  upper  and  lower  jaws  "  (Owen). 

In  the  class  of  the  Reptiles,  the  disappearance  of  the  char- 


Fig.  224. — Tooth  of  Fig.  225. — Flattened  dental  plates  of  a  Ray 

Otodus  obliquus.  (Myliobatis  Ediuardsii).     Eocene. 

Eocene. 

acteristic  Mesozoic  types  is  as  marked  a  phenomenon  as  the 
introduction  of  new  forms.  The  Ichthyosaurs,  the  Plesio- 
saurs,  the  Pterosaurs,  and  the  Mosasaurs  of  the  Mesozoic, 
find  no  representatives  in  the  Eocene  Tertiary ;  and  the  same 
is  true  of  the  Deinosaurs,  if  we  except  a  few  remains  from  the 
doubtfully-situated  "  Lignitic  formation  "  of  the  United  States. 
On  the  other  hand,  all  the  modern  orders  of  Reptiles  are 
known  to  have  existed  during  the  Eocene  period.  The 
Chelonians  are  represented  by  true  marine  Turtles,  by  "  Ter- 
rapins" (Emydidcz),  and  by  "Soft  Tortoises"  (Trionyddce]. 
The  order  of  the  Snakes  and  Serpents  (Ophidia)  makes  its 
appearance  here  for  the  first  time  under  several  forms— all  of 
which,  however,  are  referable  to  the  non-venomous  group  of 
the  "  Constricting  Serpents  "  (Boida).  The  oldest  of  these 
is  the  Palaophis  toliapiciis  of  the  London  Clay  of  Sheppey, 
first  made  known  to  science  by  the  researches  of  Professor 
Owen.  The  nearly  -  allied  Palaophis  typhaus  of  the  Eocene 
beds  of  Bracklesham  appears  to  have  been  a  Boa-constrictor- 
like  Snake  of  about  twenty  feet  in  length.  Similar  Python- 
like  Snakes  (Pal&ophis,  Dinophis,  £c.)  have  been  described 
from  the  Eocene  deposits  of  the  United  States.  True  Lizards 
(Lacertilians]  are  found  in  some  abundance  in  the  Eocene 
deposits, — some  being  small  terrestrial  forms,  like  the  common 
European  lizards  of  the  present  day  ;  whilst  others  equal  or 
exceed  the  living  Monitors  in  size.  Lastly,  the  modern  order 
of  the  Crocodilia  is  largely  represented  in  Eocene  times,  by 
species  belonging  to  all  the  existing  genera,  together  with 
others  referable  to  extinct  types.  As  pointed  out  by  Owen, 
it  is  an  interesting  fact  that  in  the  Eocene  rocks  of  the  south- 


THE    EOCENE   PERIOD. 


297 


west  of  England,  there  occur  fossil  remains  of  all  the  three 
living  types  of  Crocodilians — namely,  the  Gavials,  the  true 
Crocodiles,  and  the  Alligators  (fig.  226) —  though  at  the 


Fig.  226. — Upper  jaw  of  Alligator.     Eocene  Tertiary,  Isle  of  Wight. 

present  day  these  forms  are  all  geographically  restricted  in 
their  range,  and' are  never  associated  together. 

Almost  all  the  existing  orders  of  Birds,  if  not  all,  are 
represented  in  the  Eocene  deposits  by  remains  often  very 
closely  allied  to  existing  types.  Thus,  amongst  the  Swimming 
Birds  (Natafores)  we  find  examples  of  forms  allied  to  the 
living  Pelicans  and  Mergansers;  amongst  the  Waders  (Gral- 
latores)  we  have  birds  resembling  the  Ibis  (the  Numenius 
gypsorum  of  the  Paris  basin) ;  amongst  the  Running  Birds 
( Cursores]  we  meet  with  the  great  Gastornis  Parisiensis,  which 
equalled  the  African  Ostrich  in  height,  and  the  still  more 
gigantic  Dasornis  Londinensis  ;  remains  of  a  Partridge  rep- 
resent the  Scratching  Birds  (Rasores) ;  the  American  Eocene 
has  yielded  the  bones  of  one  of  the  Climbing  Birds  (Sca/i- 
sores],  apparently  referable  to  the  Woodpeckers ;  the  Protornis 
Glarisiensis  of  the  Eocene  Schists  of  Claris  is  the  oldest 
knowh  example  of  the  Perching  Birds  (Insessores) ;  and  the 
Birds  of  Prey  (Raptores}  are  represented  by  Vultures,  Owls, 
and  Hawks.  The  toothed  Birds  of  the  Upper  Cretaceous 
are  no  longer  known  to  exist ;  but  Professor  Owen  has 
recently  described  from  the  London  Clay  the  skull  of  a  very 
remarkable  Bird,  in  which  there  is,  at  any  rate,  an  approxi- 
mation to  the  structure  of  Ichthyornis  and  Hcsperornis.  The 
bird  in  question  has  been  named  the  Odontopteryx  toliapicus, 
its  generic  "title  being  derived  from  the  very  remarkable  char- 
acters of  its  jaws.  In  this  singular  form  (fig.  227)  the  margins 


298  HISTORICAL   PALAEONTOLOGY. 

of  both  jaws  are  furnished  with  tooth-like  denticulations,  which 
differ  from  true  teeth  in  being  actually  portions  of  the  bony 


Fig.  227. — Skull  of  Odontopteryx  toliaficus,  restored.     (After  Owen.) 

substance  of  the  jaw  itself,  with  which  they  are  continuous, 
and  which  were  probably  encased  by  extensions  of  the  horny 
sheath  of  the  bill.  These  tooth -like  processes  are  of  two 
cizes,  the  larger  ones  being  comparable  to  canines ;  and  they 
are  all  directed  forwards,  and  have  a  triangular  or  compressed 
conical  form.  From  a  careful  consideration  of  all  the  dis- 
covered remains  of  this  bird,  Professor  Owen  concludes  that 
"Odontopteryx  was  a  warm-blooded  feathered  biped,  with 
wings ;  and  further,  that  it  was  web-footed  and  a  fish-eater, 
and  that  in  the  catching  of  its  slippery  prey  it  was  assisted  by 
this  Pterosauroid  armature  of  its  jaws."  Upon  the  whole, 
Odontopteryx  would  appear  to  be  most  nearly  related  to  the 
family  of  the  Geese  (Anserince)  or  Ducks  (Anatidce) ;  but  the 
extension  of  the  bony  substance  of  the  jaws  into  tooth-like 
processes  is  an  entirely  unique  character,  in  which  it  stands 
quite  alone. 

The  known  Mammals  of  the  Mesozoic  period,  as  we  have 
seen,  are  all  of  small  size ;  and  with  one  not  unequivocal 
exception,  they  appear  to  be  referable  to  the  order  of  the 
Pouched  Quadrupeds  (Marsupials),  almost  the  lowest  group 
of  the  whole  class  of  the  Mammalia.  In  the  Eocene  rocks, 
on  the  other  hand,  numerous  remains  of  Quadrupeds  have 
been  brought  to  light,  representing  most  of  the  great  Mam- 
malian orders  now  in  existence  upon  the  earth,  and  in  many 
cases  indicating  animals  of  very  considerable  dimensions.  We 
are,  in  fact,  in  a  position  to  assert  that  the  majority  of  the 
great  groups  of  Quadrupeds  with  which  we  are  familiar  at  the 
present  day  were  already  in  existence  in  the  Eocene  period, 
and  that  their  ancient  root-stocks  were  even  in  this  early  time 
separated  by  most  of  the  fundamental  differences  of  structure 


THE   EOCENE   PERIOD.  299 

which  distinguish  their  living  representatives.  At  the  same 
time,  there  are  some  amongst  the  Eocene  quadrupeds  .which 
have  a  "  generalised  "  character,  and  which  may  be  regarded 
as  structural  types  standing  midway  between  groups  now 
sharply  separated  from  one  another. 

The  order  of  the  Marsupials — including  the  existing  Kan- 
garoos, Wombats,  Opossums,  Phalangers,  &c.  —  is  poorly 
represented  in  deposits  of  Eocene  age.  The  most  celebrated 
example  of  this  group  is  the  Didelphys  gypsorum  of  the 
Gypseous  beds  of  Montmartre,  near  Paris,  an  Opossum  very 
nearly  allied  to  the  living  Opossums  of  North  and  South 
America. 

No  member  of  the  Edentates  (Sloths,  Ant-eaters,  and  Arma- 
dillos) has  hitherto  been  detected  in  any  Eocene  deposit. 
The  aquatic  order  of  the  Sirenians  (Dugongs  and  Manatees), 
with  their  fish-like  bodies  and  tails,  paddle  -  shaped  fore- 
limbs,  and  wholly  deficient  hind-limbs,  are  represented  in 
strata  of  this  age  by  remains  of  the  ancient  "  Sea-Cows,"  to 
which  the  name  of  Halitherium  has  been  applied.  Nearly 
allied  to  the  preceding  is  the  likewise  aquatic  order  of  the 
Whales  and  Dolphins  (Cetaceans],  in  which  the  body  is  also 
fish-like,  the  hind-limbs  are  wanting,  the  fore-limbs  are  con- 
verted into  powerful  "  flippers "  or  swimming-paddles,  and 
the  terminal  extremity  of  the  body  is  furnished  with  a 
horizontal  tail-fin.  Many  existing  Cetaceans  (such  as  the 
Whalebone  Whales)  have  no  true  teeth  ;  but  others  (Dol- 
phins, Porpoises,  Sperm  Whales)  possess  simple  conical  teeth. 


Fig.   228. — Zeuglodon  eetoides.     A,   Molar  tooth  of  the  natural  size ;    B,  Vertebra, 
reduced  in  size.     From  the  Middle  Eocene  of  the  United  States.     (After  Lyell.) 

In  strata  of  Eocene  age,  however,  we  find  a  singular  group 
of   Whales,   constituting   the   genus   Zeuglodon    (fig.    228),    in 


300  HISTORICAL   PALEONTOLOGY. 

which  the  teeth  differed  from  those  of  all  existing  forms  in 
being  of  two  kinds, — the  front  ones  being  conical  incisors, 
whilst  the  back  teeth  or  molars  have  serrated  triangular 
crowns,  and  are  inserted  in  the  jaw  by  two  roots.  Each 
molar  (fig.  228,  A)  looks  as  if  it  were  composed  of  two 
separate  teeth  united  on  one  side  by  their  crowns ;  and  it  is 
this  peculiarity  which  is  expressed  by  the  generic  name  (Gr. 
zeugle,  a  yoke;  odous,  tooth).  The  be^t- known  species  of 
the  genus  is  the  Zeuglodon  cetoides  of  Owen,  which  attained 
a  length  of  seventy  feet.  Remains  of  these  gigantic  Whales 
are  very  common  in  the  "  Jackson  Beds "  of  the  Southern 
United  States.  So  common  are  they  that,  according  to  Dana, 
"  the  large  vertebrae,  some  of  them  a  foot  and  a  half  long  and 
a  foot  in  diameter,  were  formerly  so  abundant  over  the 
country,  in  Alabama,  that  they  were  used  for  making  walls,  or 
were  burned  to  rid  the  fields  of  them." 

The  great  and  important«-order  of  the  Hoofed  Quadrupeds 
( Ungiilata)  is  represented  in  the  Eocene  by  examples  of  both 
ot  its  two  principal  sections — namely,  those  with  an  uneven 
number  of  toes  (one  or  three)  on  the  foot  (Perissodacfyk  Ungu- 
lates], and  those  with  an  even  number  of  toes  (two  or  four)  to 
each  foot  (Artiodactyle  Ungulates}.  Amongst  the  Odd-toed 
Ungulates,  the  living  family  of  the  Tapirs  (Tapiridte)  is  repre- 
sented by  the  genus  Coryphodon  of  Owen.  Nearly  related  to 
the  preceding  are  the  species  of  Palceotherium,  which  have 
a  historical  interest  as  being  amongst  the  first  of  the  Tertiary 
Mammals  investigated  by  the  illustrious  Cuvier.  Several 
species  of  Palaothere  are  known,  varying  greatly  in  size,  the 
smallest  being  little  bigger  than  a  hare,  whilst  the  largest  must 
have  equalled  a  good-sized  horse  in  its  dimensions.  The 
species  of  Palceotherium  appear  to  have  agreed  with  the 
existing  Tapirs  in  possessing  a  lengthened  and  flexible  nose, 
which  formed  a  short  proboscis  or  trunk  (fig.  229),  suitable  as 
an  instrument  for  stripping  off  the  foliage  of  trees — the  char- 
acters of  the  molar  teeth  showing  them  to  have  been  strictly 
herbivorous  in  their  habits.  They  differ,  however,  from  the 
Tapirs,  amongst  other  characters,  in  the  fact  that  both  the 
fore  and  the  hind  feet  possessed  three  toes  each ;  whereas  in 
the  latter  there  are  four  toes  on  each  fore-foot,  and  the  hind- 
feet  alone  are  three-toed.  The  remains  of  PalceotJieria  have 
been  found  in  such  abundance  in  certain  localities  as  to  show 
that  these  animals  roamed  in  great  herds  over  the  fertile  plains 
of  France  and  the  south  of  England  during  the  later  portion 
of  the  Eocene  period.  The  accompanying  illustration  (fig. 
229)  represents  the  notion  which  the  great  Cuvier  was  induced 


THE   EOCENE   PERIOD. 


301 


by  bis  researches  to  form  as  to  the  outward  appearance  of 
Pafaotherium  magnum.     Recent  discoveries,   however,  have 


Fig.  229. — Outline  of  Pal<zotheriuin  magnum,  restored.     Upper  Eocene,  Europe. 
(After  Cuvier.) 

rendered  it  probable  that  this  restoration  is  in  some  important 
respects  inaccurate.  Instead  of  being  bulky,  massive,  and 
more  or  less  resembling  the  living  Tapirs  in  form,  it  would  rather 
appear  that  Palceotherium  magnum  was  in  reality  a  slender, 
graceful,  and  long-necked  animal,  more  closely  resembling  in 
general  figure  a  Llama,  or  certain  of  the  Antelopes. 

The  singular  genus  Anchitherium  forms  a  kind  of  transition 
between  the  Palceotheria  and  the  true  Horses  (Equidce).  The 
Horse  (fig.  230,  D)  possesses  but  one  fully-developed  toe  to 
each  foot,  this  being  terminated  by  a  single  broad  hoof,  and 
representing  the  middle  toe — the  third  of  the  typical  five- 
fingered  or  five-toed  limb  of  Quadrupeds  in  general.  In 
addition,  however,  to  this  fully-developed  toe,  each  foot  in 
the  horse  carries  two  rudimentary  toes  which  are  concealed 
beneath  the  skin,  and  are  known  as  the  "  splint-bones." 
These  are  respectively  the  second  and  fourth  toes,  in  an 
aborted  condition ;  and  the  frst  and  fifth  toes  are  wholly 
wanting.  In  Hipparion  (fig.  230,  C),  the  foot  is  essentially 
like  that  of  the  modern  Horses,  except  that  the  second  and 
fourth  toes  no  longer  are  mere  "  splint-bones,"  hidden  be- 
neath the  skin ;  but  have  now  little  hoofs,  and  hang  freely, 
but  uselessly,  by  the  side  of  the  great  middle  toe,  not  being 
sufficiently  developed  to  reach  the  ground.  In  Anchitherium, 
again  (fig.  230,  B),  the  foot  is  three-toed,  like  that  of  Hipparion; 
but  the  two  lateral  toes  (the  second  and  fourth)  are  so  far 


302 


HISTORICAL   PALAEONTOLOGY. 


developed  that  they  now  reach   the  ground.     The  first  digit 
(thumb  or  great  toe)  is  still  wanting  ;  as  also  is  the  fifth  digit 


„  4 


Fig.  230. — Skeleton  of  the  foot  in  various  forms  belonging  to  the  family  of  the  Eqitid(p. 
A,  Foot  of  Orohippus,  Eocene  ;  B,  Foot  of  Anchitherinm,  Upper  Eocene  and  Lower 
Miocene  ;  C,  Foot  of  Hipparion,  Upper  Miocene  and  Pliocene  ;  D,  Foot  of  Horse 
(Equus),  Pliocene  and  Recent.  The  figures  indicate  the  numbers  of  the  digits  in  the 
typical  five-fingered  hand  of  Mammals.  (After  Marsh.) 

(little  finger  or  little  toe).  Lastly,  the  Eocene  rocks  have 
yielded  in  North  America  the  remains  of  a  small  Equine 
quadruped,  to  which  Marsh  has  given  the  name  of  Orohippus. 
In  this  singular  form — which  was  not  larger  than  a  fox — the 
foot  (fig.  230,  A)  carries  four  toes,  all  of  which  are  hoofed  and 
touch  the  ground,  but  of  which  the  third  toe  is  still  the  largest. 
IL\\Q  first  toe  (thumb  or  great  toe)  is  still  wanting;  but  in  this 
ancient  representative  of  the  Horses,  the  fifth  or  "  little  "  toe 
appears  for  the  first  time.  As  all  the  above-mentioned  forms 
succeed  one  another  in  point  of  time,  it  may  be  regarded  as 
probable  that  we  shall  yet  be  able  to  point,  with  some  cer- 
tainty, to  some  still  older  example  of  the  Equidcz,  in  which 
the  first  digit  is  developed,  and  the  foot  assumes  its  typical 
five-fingered  condition. 

Passing  on  to  the  Even-toed  or  Artiodactyle  Ungulates,  no 
representative  of  the  Hippotamm  seems  yet  to  have  existed, 
but  there  are  several  forms  ( Charopotamus^  Hyopotamus,  &c.) 
more  or  less  closely  allied  to  the  Pigs  (Suida)\  and  the 
singular  group  of  the  Anoplotheridcz  may  be  regarded  as  form- 
ing a  kind  of  transition  between  the  Swine  and  the  Ruminants. 
The  Anoplotheria  (fig.  231)  were  slender  in  form,  the  largest 
not  exceeding  a  donkey  in  size,  with  long  tails,  and  having  the 
feet  terminated  by  two  hoofed  toes  each,  sometimes  with  a 
pair  of  small  accessory  hoofs  as  well.  The  teeth  exhibit  the 


THE   EOCENE   PERIOD.  303 

peculiarity  that  they  are  arranged  in  a  continuous  series,  with- 
out any  gap  or  interval  between  the  molars  and  the  canines;  and 


Fig.  231. — Aiioplotheriiiin  commune      Eocene  Tertiary,  France.     (After  Cuvier.) 

the  back  teeth,  like  those  of  all  the  Ungulates,  are  adapted  for 
grinding  vegetable  food,  their  crowns  resembling  in  form  those 
of  the  true  Ruminants.  The  genera  Dichobune  and  Xiphodon, 
of  the  Middle  and  Upper  Eocene,  are  closely  related  to 
Anoplothtrium,  but  are  more  slender  and  deer-like  in  form. 
No  example  of  the  great  Ruminant  group  of  the  Ungulate 
Quadrupeds  has  as  yet  been  detected  in  deposits  of  Eocene 
age. 

Whilst  true  Ruminants  appear  to  be  unknown,  the  Eocene 
strata  of  North  America  have  yielded  to  the  researches  of 
Professor  Marsh  examples  of  an  extraordinary  group  (Dino- 
cerata),  which  may  be  considered  as  in  some  respects  inter- 
mediate between  the  Ungulates  and  the  Proboscideans.  In 
Dinoceras  itself  (fig.  232)  we  have  a  large  animal,  equal  in 
dimensions  to  the  living  Elephants,  which  it  further  resembles 
in  the  structure  of  the  massive  limbs,  except  that  there  are 
only  four  toes  to  each  foot.  The  upper  jaw  was  devoid  of 
front  teeth,  but  there  were  two  very  large  canine  teeth,  in  the 
form  of  tusks  directed  perpendicularly  downwards ;  and  there 
was  also  a  series  of  six  small  molars  on  each.  Each  upper 
jaw-bone  carried  a  bony  projection,  which  was  probably  of  the 
nature  of  a  "  horn  core,"  and  was  originally  sheathed  in  horn. 
Two  similar,  but  smaller,  horn-cores  are  carried  on  the  nasal 
bones;  and  two  much  larger  projections,  also  probably  of  the 
nature  of  horn-cores,  were  carried  upon  the  forehead.  We 
may  thus  infer  that  Dinoceras  possessed  three  pairs  of  horns, 
all  of  which  resembled  the  horns  of  the  Sheep  and  Oxen  in 
consisting  of  a  central  bony  "core,"  surrounded  by  a  horny 


304 


HISTORICAL    PALAEONTOLOGY. 


sheath.      The  nose  was  not  prolonged  into  a   proboscis   or 
"  trunk,"  as  in  the  existing  Elephants ;  and  the  tail  was  short 


Fig.  232. — Skull  of  Dinoceras  mirabilis,  greatly  reduced.     Eocene,  North  America. 
(After  Marsh.) 

and  slender.  Many  forms  of  the  Dinoccrata  are  known  ;  but  all 
these  singular  and  gigantic  quadrupeds  appear  to  have  been 
confined  to  the  North  American  continent,  and  to  be  restricted 
to  the  Eocene  period. 

The  important  order  of  the  Elephants  (Probosridea)  is  also 
not  known  to  have  come  into  existence  during  the  Eocene 
period.  On  the  other  hand,  the  great  order  of  the  Beasts  of 
Prey  (Carnivora)  is  represented  in  Eocene  strata  by  several 
forms  belonging  to  different  types.  Thus  the  Arctocyon  pre- 
sents us  with  an  Eocene  Carnivore  more  or  less  closely  allied 
to  the  existing  Racoons  ;  the  Pal&onyctis  appears  to  be  related 
to  the  recent  Civet-cats ;  the  genus  Hycenodon  is  in  some 
respects  comparable  to  the  living  Hyaenas  ;  and  the  Canis 
Parisiensis  of  the  gypsum-bearing  beds  of  Montmartre  may 
perhaps  be  allied  to  the  Foxes. 

The  order  of  the  Bats  ( Cheiroptera]  is  represented  in  Eocene 
strata  of  the  Paris  basin  (Gypseous  series  of  Montmartre)  by 
the  Vespertilio  Parisiensis  (fig.  233),  an  insect-eating  Bat  very 
similar  to  some  of  the  existing  European  forms.  Lastly,  the 
Eocene  deposits  have  yielded  more  or  less  satisfactory  evi- 


THE    MIOCENE   PERIOD.  305 

dence  of  the  existence  in  Europe  at  this  period  of  examples  of 
the  orders  of  the  Gnawing  Mammals  (Rodentia),  the  Insect- 


Fig-  233.— Portion  of  the  skeleton  of  Vespertilio  Parisiensis.     Eocene  Tertiary,  France. 

eating   Mammals    (Insect ivora),   and    the    Monkeys   (Quadru- 
mana).* 


CHAPTER     XIX. 

THE  MIOCENE  PERIOD. 

The  Miocene  rocks  comprise  those  Tertiary  deposits  which 
contain  less  than  about  3 5  per  cent  of  existing  species  of  shells 
(Mollusca\  and  more  than  5  per  cent — or  those  deposits  in 
which  the  proportion  of  living  shells  is  less  than  of  extinct 
species.  They  are  divisible  into  a  Lower  Miocene  ( Oligocene) 
and  an  Upper  Miocene  series. 

In  Britain,  the  Miocene  rocks  are  very  poorly  developed, 
one  of  their  leading  developments  being  at  Bovey  Tracy  in 
Devonshire,  where  there  occur  sands,  clays,  and  beds  of  lignite 

*  A  short  list  of  the  more  important  works  relating  to  the  Eocene 
rocks  and  fossils  will  be  given  after  all  the  Tertiary  deposits  have  been 
treated  of. 


306  HISTORICAL   PALAEONTOLOGY. 

or  imperfect  coal.  These  strata  contain  numerous  plants, 
amongst  which  are  Vines,  Figs,  the  Cinnamon-tree,  Palms, 
and  many  Conifers,  especially  those  belonging  to  the  genus 
Sequoia  (the  "Red-woods").  These  Bovey  Tracy  lignites  are 
of  Lower  Miocene  age,  and  they  are  lacustrine  in  origin.  Also 
of  Lower  Miocene  age  are  the  so-called  "  Hempstead  Beds  " 
of  Yarmouth  in  the  Isle  of  Wight.  These  attain  a  thickness  of 
less  than  200  feet,  and  are  shown  by  their  numerous  fossils  to 
be  principally  a  true  marine  formation.  Lastly,  the  Duke  of 
Argyll,  in  1851,  showed  that  there  existed  at  Ardtun,  in  the 
island  of  Mull,  certain  Tertiary  strata  containing  numerous 
remains  of  plants  ;  and  these  also  are  now  regarded  as  belong- 
ing to  the  Lower  Miocene. 

In  France,  the  Lower  Miocene  is  represented  in  Auvergne, 
Cantal,  and  Velay,  by  a  great  thickness  of  nearly  horizontal 
strata  of  sands,  sandstone,  clays,  marls,  and  limestones,  the 
whole  of  fresh-water  origin.  The  principal  fossils  of  these 
lacustrine  deposits  are  Mammalia,  of  which  the  remains  occur 
in  great  abundance.  In  the  valley  of  the  Loire  occur  the 
typical  European  deposits  of  Upper  Miocene  age.  These  are 
known  as  the  "  Faluns,"  from  a  provincial  term  applied  to 
shelly  sands,  employed  to  spread  upon  soils  which  are  deficient 
in  lime ;  and  the  Upper  Miocene  is  hence  sometimes  spoken 
of  as  the  "  Falun ian  "  formation.  The  Faluns  occur  in  scat- 
tered patches,  which  are  rarely  more  than  50  feet  in  thickness, 
and  consist  of  sands  and  marls.  The  fossils  are  chiefly  marine; 
but  there  occur  also  land  and  fresh-water  shells,  together  with 
the  remains  of  numerous  Mammals.  About  25  per  cent  of  the 
shells  of  the  Faluns  are  identical  with  existing  species.  The 
sands,  limestones,  and  marls  of  the  Department  of  Gers,  near 
the  base  of  the  Pyrenees,  rendered  famous  by  the  number  of 
Mammalian  remains  exhumed  from  them  by  M.  Lartet,  also 
belong  to  the  age  of  the  Faluns. 

In  Switzerland,  between  the  Alps  and  the  Jura,  there  occurs 
a  great  series  of  Miocene  deposits,  known  collectively  as  the 
"  Molasse,"  from  the  soft  nature  of  a  greenish  sandstone, 
which  constitutes  one  of  its  chief  members.  It  attains  a  thick- 
ness of  many  thousands  of  feet,  and  rises  into  lofty  mountains, 
some  of  which — as  the  Rigi — are  more  than  6000  feet  in 
height.  The  middle  portion  of  the  Molasse  is  of  marine 
origin,  and  is  shown  by  its  fossils  to  be  of  the  age  of  the 
Faluns;  but  the  lower  and  upper  portions  of  the  formation 
are  mainly  or  entirely  of  fresh -water  origin.  The  Lower 
Molasse  (of  Lower  Miocene  age)  has  yielded  about  500  species 
of  plants,  mostly  of  tropical  or  sub-tropical  forms.  The  Upper 


THE   MIOCENE   PERIOD.  307 

Molasse  has  yielded  about  the  same  number  of  plants,  with 
about  900  species  of  Insects,  such  as  wood-eating  Beetles 
Water-beetles,  White  Ants,  Dragon-flies,  &c. 

In  Belgium,  strata  of  both  Lower  and  Upper  Miocene  age 
are  known, — the  former  (Rupelian  Clays)  containing  numerous 
marine  fossils ;  whilst  the  latter  {Bolderberg  Sands)  have 
yielded  numerous  shells  corresponding  with  those  of  the 
Faluns. 

In  Austria,  Miocene  strata  are  largely  developed,  marine 
beds  belonging  to  both  the  Lower  and  Upper  division  of  the 
formation  occurring  extensively  in  the  Vienna  basin.  The 
well-known  Brown  Coals  of  Radaboj,  in  Croatia,  with  numer- 
ous plants  and  insects,  are  also  of  Lower  Miocene  age. 

In  Germany,  deposits  belonging  to  both  the  Lower  and 
Upper  division  of  the  Miocene  formation  are  extensively  de- 
veloped. To  the  former  belong  the  marine  strata  of  the  May- 
ence  basin,  and  the  marine  Rupelian  Clay  near  Berlin  ;  whilst 
a  celebrated  group  of  strata  belonging  to  the  Upper  Miocene 
occurs  near  Epplesheim,  in  Hesse- Darmstadt,  and  is  well 
known  for  the  number  of  its  Mammalian  remains. 

In  Greece,  at  Pikerme,  near  Athens,  there  occurs  a  celebrated 
deposit  of  Upper  Miocene  age,  well  known  to  palaeontologists 
through  the  researches  of  M.M.  Wagner,  Roth,  and  Gaudry 
upon  the  numerous  Mammalia  which  it  contains.  In  Italy, 
also,  strata  of  both  Lower  and  Upper  Miocene  age  are  well 
developed  in  the*  neighbourhood  of  Turin. 

In  the  Siwalik  Hills,  in  India,  at  the  southern  foot  of  the 
Himalayas,  occurs  a  series  of  Upper  Miocene  strata,  which 
have  become  widely  celebrated  through  the  researches  of  Dr 
Falconer  and  Sir  Proby  Cautley  upon  the  numerous  remains 
of  Mammals  and  Reptiles  which  they  contain.  Beds  of  corre- 
sponding age,  with  similar  fossils,  are  known  to  occur  in  the 
island  of  Perim  in  the  Gulf  of  Cambay. 

Lastly,  Miocene  deposits  are  found  in  North  America,  in 
New  Jersey,  Maryland,  Virginia,  Missouri,  California,  Oregon, 
&c.,  attaining  a  thickness  of  1500  feet  or  more.  They  consist 
principally  of  clays,  sands,  and  sandstones,  sometimes  of 
marine  and  sometimes  of  fresh-water  origin.  Near  Richmond, 
in  Virginia,  there  occurs  a  remarkable  stratum,  wrongly  called 
"  Infusorial  Earth,"  which  is  occasionally  30  feet  in  thickness, 
and  consists  almost  wholly  of  the  siliceous  envelopes  of  cer- 
tain low  forms  of  plants  (Diatoms),  along  with  the  spicules  of 
Sponges  and  other  siliceous  organisms  (see  fig.  16).  The 
White  River  Group  of  Hayden  occurs  in  the  Upper  Missouri 
region,  and  is  largely  exposed  over  the  barren  and  desolate 


308  HISTORICAL   PALEONTOLOGY. 

district  known  as  the  "  Mauvaises  Terres."  They  have  a 
thickness  of  1000  feet  or  more,  and  contain  numerous  remains 
of  Mammals.  They  are  of  lacustrine  origin,  and  are  believed 
to  be  of  the  age  of  the  Lower  Miocene.  Upon  the  whole, 
about  from  15  to  30  per  cent  of  the  Mollusca  of  the  American 
Miocene  are  identical  with  existing  species. 

In  addition  to  the  regions  previously  enumerated,  Miocene 
strata  are  known  to  be  developed  in  Greenland,  Iceland,  Spitz- 
bergen,  and  in  other  areas  of  less  importance. 

The  life  of  the  Miocene  period  is  extremely  abundant,  and, 
from  the  nature  of  the  deposits  of  this  age,  also  extremely 
varied  in  its  character.  The  marine  beds  of  the  formation 
have  yielded  numerous  remains  of  both  Vertebrate  and  Inver- 
tebrate sea-animals ;  whilst  the  fresh-water  deposits  contain 
the  skeletons  of  such  shells,  fishes,  &c.,  as  now  inhabit  rivers 
or  lakes.  Both  the  marine  and  the  lacustrine  beds  have  been 
shown  to  contain  an  enormous  number  of  plants,  the  latter 
more  particularly  ;  whilst  the  Brown  Coals  of  the  formation 
are  made  up  of  vegetable  matter  little  altered  from  its  original 
condition.  The  remains  of  air-breathing  animals,  such  as 
Insects,  Reptiles,  Birds,  and  Mammals,  are  also  abundantly 
found,  more  especially  in  the  fresh-water  beds. 

The  plants  of  the  Miocene  period  are  extraordinarily  num- 
erous, and  only  some  of  the  general  features  of  the  vegetation  of 
this  epoch  can  be  indicated  here.  Our  chief  sources  of  informa- 
tion as  to  the  Miocene  plants  are  the  Brown  Coals  of  Germany 
and  Austria,  the  Lower  and  Upper  Molasse  of  Switzerland, 
and  the  Miocene  strata  of  the  Arctic  regions.  The  lignites  of 
Austria  have  yielded  very  numerous  plants,  chiefly  of  a  tropical 
character — one  of  the  most  noticeable  forms  being  a  Palm  of 
the  genus  Sabal  (fig.  234,  B),  now  found  in  America.  The 
plants  of  the  Lower  Miocene  of  Switzerland  are  also  mostly 
of 'a  tropical  character,  but  include  several  forms  now  found 
in  North  America,  such  as  a  Tulip-tree  (Liriodendron)  and  a 
Cypress  (Taxodium).  Amongst  the  more  remarkable  forms 
from  these  beds  maybe  mentioned  Fan-Palms  (Chamarops, 
fig  234,  A),  numerous  tropical  ferns,  and  two  species  of  Cin- 
namon. The  plant-remains  of  the  Upper  Molasse  of  Switzer- 
land indicate  an  extraordinarily  rank  and  luxuriant  vegetation, 
composed  mainly  of  plants  which  now  live  in  warm  countries. 
Among  the  commoner  plants  of  this  formation  may  be  enume- 
rated many  species  of  Maple  (Acer),  Plane-trees  (Platanus 
fig.  235),  Cinnamon-trees  (fig.  236),  and  other  members  of  the 
Lauracece,  many  species  of  Proteaccce  (Banksia,  Grevillea,  &c. ), 
several  species  of  Sarsaparilla  (Smi/ax),  Palms,  Cypresses,  &c. 


THE    MIOCENE    PERIOD. 


309 


In  Britain,  the  Lower  Miocene  strata  of  Bovey  Tracy  have 
yielded  remains  of  Ferns,  Vines,  Fig,   Cinnamon,  Proteacece, 


Palms      A,  Chamterops  Helvetica  ;  B,  Sabai  major. 
of  Switzerland  and  FYanr_e. 


Fig.  234. — Miocene  Palms      A,  Chamcprops  Helvetica  ;  B, 
Lower  Miocene  of  Switzerland  and  France. 


&c.,  along  with  numerous  Conifers.     The  most  abundant  of 
these  last  is  a  gigantic  pine — the  Sequoia   Couttsice— which  is 


F,g.  235. — Plataims  nceroides,  an 
Upper  Miocene  Plane-tree,  a,  Leaf; 
b,  The  core  of  a  bundle  of  fruits ;  c, 
A  single  fruit. 


Fig.  236.  —  Cinnamo- 
IHUIII  polymorphum.  a, 
Leaf;  b,  Flower.  Upper 
Miocene. 


very  nearly  allied,  to  the  huge  Sequoia  ( WeUingtonia)  gigantea 
of  California.  A  nearly-allied  form  {Sequoia  Langsdorjfi}  has 
been  detected  in  the  leaf-bed  of  Ardtun,  in  the  Hebrides. 

In  Greenland,  as  well  as  in  other  parts  of  the  Arctic  regions, 
Miocene  strata  have  been  discovered  which  have  yielded  a 
great  number  of  plants,  many  of  which  are  identical  with 
species  found  in  the  European  Miocene.  Amongst  these 


310  HISTORICAL   PALAEONTOLOGY. 

plants  are  found  many  trees,  such  as  Conifers,  Beeches,  Oaks, 
Maples,  Plane-trees,  Walnuts,  Magnolias,  &c.,  with  numerous 
shrubs,  ferns,  and  other  smaller  plants.  With  regard  to  the 
Miocene  flora  of  the  Arctic  regions,  Sir  Charles  Lyell  remarks 
that  "more  than  thirty  species  of  Coniferae  have  been  found, 
including  several  Sequoias  (allied  to  the  gigantic  Wellingtonia 
of  California),  with  species  of  Thujopsis  and  Salisburia^  now 
peculiar  to  Japan.  There  are  also  beeches,  oaks,  planes, 
poplars,  maples,  walnuts,  limes,  and  even  a  magnolia,  two 
cones  of  which  have  recently  been  obtained,  proving  thp.t 
this  splendid  evergreen  not  only  lived  but  ripened  its  fruit 
within  the  Arctic  circle.  Many  of  the  limes,  planes,  and 
oaks  were  large-leaved  species ;  and  both  flowers  and  fruits, 
besides  immense  quantities  of  leaves,  are  in  many  cases  pre- 
served. Among  the  shrubs  are  many  evergreens,  as  Andro- 
meda, and  two  extinct  genera,  Daphnogene  and  M'Clintockia, 
with  fine  leathery  leaves,  together  with  hazel,  blackthorn, 
holly,  logwood,  and  hawthorn.  A  species  of  Zamia  (Zamitcs) 
grew  in  the  swamps,  with  Potamogdon,  Sparganium,  and 
Menyanthes ;  while  ivy  and  vines  twined  around  the  forest- 
trees,  and  broad-leaved  ferns  grew  beneath  their  shade.  Even 
in  Spitzbergen,  as  far  north  as  lat.  78°  56',  no  less  than  ninety- 
five  species  of  fossil  plants  have  been  obtained,  including 
Taxodium  of  two  species,  hazel,  poplar,  alder,  beech,  plane- 
tree,  and  lime.  Such  a  vigorous  growth  of  trees  within  12°  of 
the  pole,  where  now  a  dwarf  willow  and  a  few  herbaceous 
plants  form  the  only  vegetation,  and  where  the  ground  is 
covered  with  almost  perpetual  snow  and  ice,  is  truly  remark- 
able." 

Taking  the  Miocene  flora  as  a  whole,  Dr  Heer  concludes 
from  his  study  of  about  3000  plants  contained  in  the  Euro- 
pean Miocene  alone,  that  the  Miocene  plants  indicate  tropical 
or  sub-tropical  conditions,  but  that  there  is  a  striking  inter- 
mixture of  forms  which  are  at  present  found  in  countries 
widely  removed  from  one  another.  It  is  impossible  to  state 
with  certainty  how  many  of  the  Miocene  plants  belong  to 
existing  species,  but  it  appears  that  the  larger  number  are 
extinct.  According  to  Heer,  the  American  types  of  plants 
are  most  largely  represented  in  the  Miocene  flora,  next  those 
of  Europe  and  Asia,  next  those  of  Africa,  and  lastly  those  of 
Australia.  Upon  the  whole,  however,  the  Miocene  flora  of 
Europe  is  mostly  nearly  allied  to  the  plants  which  we  now 
find  inhabiting  the  warmer  parts  of  the  United  States  \  and 
this  has  led  to  the  suggestion  that  in  Miocene  times  the 
Atlantic  Ocean  was  dry  land,  and  that  a  migration  of  Ameri- 


THE   MIOCENE   PERIOD.  311 

can  plants  to  Europe  was  thus  permitted.  This  view  is  borne 
out  by  the  fact  that  the  Miocene  plants  of  Europe  are  most 
nearly  allied  to  the  living  plants  of  the  eastern  or  Atlantic 
seaboard  of  the  United  States,  and  also  by  the  occurrence  of 
a  rich  Miocene  flora  in  Greenland.  As  regards  Greenland, 
Dr  Heer  has  determined  that  the  Miocene  plants  indicate  a 
temperate  climate  in  that  country,  with  a  mean  annual  tem- 
perature at  least  30°  warmer  than  it  is  at  present. 

The  present  limit  of  trees  is  the  isothermal  which  gives  the 
mean  temperature  of  50°  Fahr.  in  July,  or  about  the  parallel 
of  67°  N.  latitude.  In  Miocene  times,  however,  the  Limes, 
Cypresses,  and  Plane-trees  reach  the  79th  degree  of  latitude, 
and  the  Pines  and  Poplars  must  have  ranged  even  further 
north  than  this. 

The  Invertebrate  Animals  of  the  Miocene  period  are  very 
numerous,  but  they  belong  for  the  most  part  to  existing  types, 
and  they  can  only  receive  scanty  consideration  here.  The 
little  shells  of  Foraminifera  are  extremely  abundant  in  some 
beds,  the  genera  being  in  many  cases  such  as  now  flourish 
abundantly  in  our  seas.  The  principal  forms  belong  to  the 
genera  Textularia  (fig.  237),  Rolmlina,  Glandulina,  Poly- 
stomella,  Amphistegina,  &c. 
Corals  are  very  abundant, 
in  many  instances  forming 
regular  "  reefs  ;"  but  all  the 
more  important  groups  are 
in  existence  at  the  present 
day.  The  Red  Coral  (Cor- 
allium),  so  largely  sought 
after  as  an  ornamental  ma- 
terial, appears  for  the  first 
time  in  deposits  of  this  age. 
Amongst  the  Echinoderms, 
we  meet  with  Heart -Urchins  (Spatangus),  Cake -Urchins 
(Scutella,  fig.  238),  and  various  other  forms,  the  majority  of 
which  are  closely  allied  to  forms  now  in  existence. 

Numerous  Crabs  and  Lobsters  represent  the  Crustacea;  but 
the  most  important  of  the  Miocene  Articulate  Animals  are  the 
Insects.  Of  these,  more  than  thirteen  hundred  species  have 
been  determined  by  Dr  Heer  from  the  Miocene  strata  of 
Switzerland  alone.  They  include  almost  all  the  existing 
orders  of  insects,  such  as  numerous  and  varied  forms  of 
Beetles  (Coleopterd),  Forest-bugs  (Hemiptera},  Ants  (Hymen- 
opterd],  Flies  (Diptera\  Termites  and  Dragon -flies  (Neurop- 
tera\  Grasshoppers  (Orthoptera).  and  Butterflies  (Lepidopterd). 


3I2 


HISTORICAL   PALEONTOLOGY. 


One  of  the  latter,  the  well-known  Vanessa  Pluto  of  the  Brown 
Coals  of  Croatia,  even  exhibits  the  pattern  of  the  wing,  and  to 


Fig.  238. — Different  views  of  Scntella  subroiunda,  a  Miocene  "Cake-Urchin" 
from  the  south  of  France. 

some  extent  its  original  coloration ;  whilst  the  more  durably- 
constructed  insects  are  often  in  a  state  of  exquisite  preser- 
vation. 

The  Mollusca  of  the  Miocene  period  are  very  numerous, 
but  call  for  little  special  comment.  Upon  the  whole,  they  are 
generically  very  similar  to  the  Shell-fish  of  the  present  day ; 
whilst,  as  before  stated,  from  fifteen  to  thirty  per  cent  of  the 
species  are  identical  with  those  now  in  existence.  So  far  as  the 
European  area  is  concerned,  the  Molluscs  indicate  a  decidedly 
hotter  climate  than  the  present  one,  though  they  have  not  such 
a  distinctly  tropical  character  as  is  the  case  with  the  Eocene 
shells.  Thus  we  meet  with  many  Cones,  Volutes,  Cowries, 
Olive-shells,  Fig-shells,  and  the  like,  which  are  decidedly 
indicative  of  a  high  temperature  of  the  sea.  Polyzoaus  are 
abundant,  and  often  attain  considerable  dimensions ;  whilst 
Bracktopods,  on  the  other  hand,  are  few  in  number.  Bivalves 
and  Univalves  are  extremely  plentiful ;  and  we  meet  here  with 
the  shells  of  Winged  -  Snails  (PUropods)t  belonging  to  such 
existing  genera  as  Hyalea  (fig.  239)  and  Cleodora.  Lastly, 

the  Cephalopods  are  represent- 
ed both  by  the  chambered 
shells  of  Nautili  and  by  the 
internal  skeletons  of  Cuttle- 
fishes (Spirulirostra. ) 

The  Pishes  of  the  Miocene 
period  are  very  abundant,  but 
of  little  special  importance. 
Besides  the  remains  of  Bony  Fishes,  we  meet  in  the  marine 
deposits  of  this  age  with  numerous  pointed  teeth  belonging 
to  different  kinds  of  Sharks.  Some  of  the  genera  of  these — 
such  as  Carcharodon  (fig.  241),  Oxyrhina  (fig.  240),  Lamna, 
and  Galeocerdo — are  very  widely  distributed,  ranging  through 


g.   239. — Different  views  of  the  shell 
Hyalea     Orbignyana,     a     Miocene 


Fi 

of    HyaL 
Pteropod. 


A 


THE   MIOCENE  PERIOD.  313 

both  the  Old  and  New  Worlds  ;  and  some  of  the  species  attain 
gigantic  dimensions. 

Amongst  the  Amphibians  we  meet  with  distinctly  modern 
types,  such  as  Frogs  (Rana) 
and  Newts  or  Salamanders. 
The  most  celebrated  of  the 
latter  is  the  famous  Andrias 
Scheuchzeri  (fig.  242),  dis- 
covered in  the  year  1725 
in  the  fresh-water  Miocene 
deposits  of  OEningen,  in 
Switzerland.  The  skeleton 
indicates  an  animal  nearly 
five  feet  in  length;  and  it  Fig.  240.— Tooth  Fig.  241.— Tooth 
was  originally  described  by  £*&•**•.  ^fTStSST 
Scheuchzer,  a  Swiss  physi- 
cian, in  a  dissertation  published  in  1731,  as  the  remains  of  one 
of  the  human  beings  who  were  in  existence  at  the  time  of  the 
Noachian  Deluge.  Hence  he  applied  to  it  the  name  of  Homo 
diluvii  testis.  In  reality,  however,  as  shown  by  Cuvier,  we 
have  here  the  skeleton  of  a  huge  Newt,  very  closely  allied  to 
the  Giant  Salamander  (Menopoma  maxima)  of  Java. 

The  remains  of  Reptiles  are  far  from  uncommon  in  the 
Miocene  rocks,  consisting  principally  of  Chelonians  and  Cro- 
codilians.  The  Land-tortoises  (Testudinidce)  make  their  first 
appearance  during  this  period.  The  most  remarkable  form 
of  this  group  is  the  huge  Colossochelys  Atlas  of  the  Upper 
Miocene  deposits  of  the  Siwalik  Hills  in  India,  described  by 
Dr  Falconer  and  Sir  Proby  Cautley.  Far  exceeding  any 
living  Tortoise  in  its  dimensions,  this  enormous  animal  is 
estimated  as  having  had  a  length  of  about  twenty  feet,  measured 
from  the  tip  of  the  snout  to  the  extremity  of  the  tail,  and  to 
have  stood  upwards  of  seven  feet  high.  All  the  details  of  its 
organisation,  however,  prove  that  it  must  have  been  "  strictly 
a  land  animal,  with  herbivorous  habits,  and  probably  of  the 
most  inoffensive  nature."  The  accomplished  palaeontologist 
just  quoted,  shows  further  that  some  of  the  traditions  of  the 
Hindoos  would  render  it  not  improbable  that  this  colossal 
Tortoise  had  survived  into  the  earlier  portion  of  the  human 
period. 

Of  the  Birds  of  the  Miocene  period  it  is  sufficient  to  re- 
mark that  though  specifically  distinct,  they  belong,  so  far  as 
known,  wholly  to  existing  groups,  and  therefore  present  no 
points  of  special  palseontolgical  interest. 

The  Mammals  of  the  Miocene  are  very  numerous,  and  only 


HISTORICAL   PALAEONTOLOGY. 


Fig.  242.— Front  portion  of  the  skeleton  of  Andrias  S elicit chzcri.  a  Giant  Salamander 
from  the  Miocene  Tertiary  of  CEningen,  in  Switzerland.     Reduced  in  size. 


THE   MIOCENE   PERIOD.  315 

the  more  important  forms  can  be  here  alluded  to.  Amongst 
the  Marsupials,  the  Old  World  still  continued  to  possess 
species  of  Opossum  (Didephys),  allied  to  the  existing  American 
forms.  The  Edentates  (Sloths,  Armadillos,  and  Ant-eaters),  at 
the  present  day  mainly  South  American,  are  represented  by 
two  large  European  forms.  One  of  these  is  the  large  Macro- 
therium  giganteum  of  the  Upper  Miocene  of  Gers  in  Southern 
France,  which  appears  to  have  been  in  many  respects  allied  to 
the  existing  Scaly  Ant-eaters  or  Pangolins,  at  the  same  time 
that  the  disproportionately  long  fore-limbs  would  indicate  that 
it  possessed  the  climbing  habits  of  the  Sloths.  The  other  is 
the  still  more  gigantic  Ancytoiherium  Pentelid  of  the  Upper 
Miocene  of  Pikerme,  which  seems  to  have  been  as  large  as,  or 
larger  than,  the  Rhinoceros,  and  which  must  have  been  terres- 
trial in  its  habits.  This  conclusion  is  further  borne  out  by  the 
comparative  equality  of  length  which  subsists  between  the  fore 
and  hind  limbs,  and  is  not  affected  by  the  curvature  and 
crookedness  of  the  claws,  this  latter  feature  being  well  marked 
in  such  existing  terrestrial  Edentates  as  the  Great  Ant  eater. 

The  aquatic  Sirenians  and  Cdaccans  are  represented  in 
Miocene  times  by  various  forms  of  no  special  importance. 
Amongst  the  former,  the  previously  existing  genus  Haiti Jierium 
continued  to  survive,  and  amongst  the  latter  we  meet  with 
remains  of  Dolphins  and  of  Whales  of  the  "Zeuglodont" 
family.  We  may  also  note  here  the  first  appearance  of  true 
"  Whalebone  Whales,"  two  species  of  which,  resembling  the 
living  "  Right  Whale"  of  Arctic  seas,  and  belonging  to  the 
same  genus  (Balana],  have  been  detected  in  the  Miocene 
beds  of  North  America. 

The  great  order  of  the  Ungulates  or  Hoofed  Quadrupeds  is 
very  largely  developed  in  strata  of  Miocene  age,  various  new 
types  of  this  group  making  their  appearance  here  for  the  first 
time,  whilst  some  of  the  characteristic  genera  of  the  preceding 
period  are  still  represented  under  new  shapes.  Amongst  the. 
Odd-toed  or  "  Perissodactyle  "  Ungulates,  we  meet  for  the  first 
time  with  representatives  of  the  family  Rhinoccridcs  compris- 
ing only  the  existing  Rhinoceroses.  In  India  in  the  Upper 
Miocene  beds  of  the  Siwalik  Hills,  and  in  North  America, 
several  species  of  Rhinoceros  have  been  detected,  agreeing  with 
the  existing  forms  in  possessing  three  toes  to  each  foot,  and  in 
having  one  or  two  solid  fibrous  "  horns  "  carried  upon  the  front 
of  the  head.  On  the  other  hand,  the  forms  of  this  group  which 
distinguish  the  Miocene  deposits  of  Europe  appear  to  have 
been  for  the  most  part  hornless,  and  to  have  resembled  the 
Tapirs  in  having  three- toed  hind-feet,  but  four- toed  fore-feet. 


316  HISTORICAL   PALAEONTOLOGY. 

The  family  of  the  Tapirs  is  represented,  both  in  the  Old 
and  New  Worlds,  by  species  of  the  genus  Lophiodon,  some  of 
which  were  quite  diminutive  in  point  of  size,  whilst  others 
attained  the  dimensions  of  a  horse.  Nearly  allied  to  this 
family,  also,  is  the  singular  group  of  quadrupeds  which  Marsh 
has  described  from  the  Miocene  strata  of  the  United  States 
under  the  name  of  Brontotheridce.  These  extraordinary  ani- 
mals, typified  by  Brontotherium  (fig.  243)  itself,  agree  with  the 


Fig.  243. — Skull  of  Brontotherium  ing-ens.     Miocene  Tertiary,  United  States. 
(After  Marsh.) 

existing  Tapirs  of  South  America  and  the  Indian  Archipelago 
in  having  the  fore-feet  four-toed,  whilst  the  hind-feet  are  three- 
toed  ;  and  a  further  point  of  resemblance  is  found  in  the  fact 
(as  shown  by  the  form  of  the  nasal  bones)  that  the  nose  was 
long  and  flexible,  forming  a  short  movable  proboscis  or  trunk, 
by  means  of  which  the  animal  was  enabled  to  browse  on 
shrubs  or  trees.  They  differ,  however,  from  the  Tapirs,  not 
only  in  the  apparent  presence  of  a  long  tail,  but  also  in  the 
possession  of  a  pair  of  very  large  "  horn-cores,"  carried  upon 
the  nasal  bones,  indicating  that  the  animal  possessed  horns  of 
a  similar  structure  to  those  of  the  "Hollow-horned"  Rumin- 
ants (e.g.,  Sheep  and  Oxen).  Brontotherium  gigas  is  said  to  be 
nearly  as  large  as  an  Elephant,  whilst  B.  ingens  appears  to 
have  attained  dimensions  still  more  gigantic.  The  well-known 
genus  Titanotkerium  of  the  American  Miocene  would  also 
appear  to  belong  to  this  group. 

The  family  of  the  Horses  (Equidce]  appears  under  various 
forms  in  the  Miocene,  but  the  most  important  and  best  known 
of  these  is  Hipparion.  In  this  genus  the  general  conformation 
of  the  skeleton  is  extremely  similar  to  that  of  the  existing 
Horses,  and  the  external  appearance  of  the  animal  must  have 
been  very  much  the  same.  The  foot  of  Hipparion,  however, 


THE   MIOCENE   PERIOD.  317 

as  has  been  previously  mentioned,  differed  from  that  of  the 
Horse  in  the  fact  that  whilst  both  possess  the  middle  toe  greatly 
developed  and  enclosed  in  a  broad  hoof,  the  former,  in  addition, 
possessed  two  lateral  toes,  which  were  sufficiently  developed 
to  carry  hoofs,  but  were  so  far  rudimentary  that  they  hung  idly 
by  the  side  of  the  central  toe  without  touching  the  ground 
(see  fig.  230).  In  the  Horse,  on  the  other  hand,  these  lateral 
toes,  though  present,  are  not  only  functionally  useless,  but  are 
concealed  beneath  the  skin.  Remains  of  the  Hipparion  have 
been  found  in  various  regions  in  Europe  and  in  India ;  and 
from  the  immense  quantities  of  their  bones  found  in  certain 
localities,  it  may  be  safely  inferred  that  these  Middle  Tertiary 
ancestors  of  the  Horses  lived,  like  their  modern  representa- 
tives, in  great  herds,  and  in  open  grassy  plains  or  prairies. 

Amongst  the  Even-toed  or  Artiodactyle  Ungulates,  we  for 
the  first  time  meet  with  examples  of  the  Hippopotamus,  with  its 
four-toed  feet,  its  massive  body,  and  huge  tusk-like  lower 
canine  teeth.  The  Miocene  deposits  of  Europe  have  not 
hitherto  yielded  any  remains  of  Hippopotamus ;  but  several 
species  have  been  detected  in  the  Upper  Miocene  of  the  Siwalik 
Hills  by  Dr  Falconer  and  Sir  Proby  Cautley.  These  ancient 
Indian  forms,  however,  differ  from  the  existing  Hippopotamus 
amphibius  of  Africa  in  the  fact  that  they  possessed  six  incisor 
teeth  in  each  jaw  (fig.  244),  whereas  the  latter  has  only  four. 

Amongst  the  other  Even-toed  Ungulates,  the  family  of  the 
Pigs  (Suida)  is  represented  by  true  Swine  (Sus  Erymanthius}, 
Peccaries  (Dicotyles  antiquus\  and  by  forms  which,  like  the 
great  Elotherium  of  the  American  Miocene,  have  no  represen- 
tative at  the  present  day.  The  Upper  Miocene  of  India  has 
yielded  examples  of  the  Camels,  Small  Musk-deer  (Amphi- 
tragulus  and  Dremotherium]  are  known  to  have  existed  in 
France  and  Greece  ;  and  the  true  Deer  ( Cervidce),  with  their 
solid  bony  antlers,  appear  for  the  first  time  here  in  the  person  of 
species  allied  to  the  living  Stags  {Cervus\  accompanied  by  the 
extinct  genus  Dorcatherium.  The  Giraffes  (Camelopardaiida), 
now  confined  to  Africa,  are  known  to  have  lived  in  India  and 
Greece ;  and  the  allied  Hdladothcrium,  in  some  repects  inter- 
mediate between  the  Giraffes  and  the  Antelopes,  ranged  over 
Southern  Europe  from  Attica  to  France.  The  great  group  of 
the  "Hollow-horned"  Ruminants  (Cavicornia\  lastly,  came 
into  existence  in  the  Miocene  period ;  and  though  the  typical 
families  of  the  Sheep  and  Oxen  are  apparently  wanting,  there 
are  true  Antelopes,  together  with  forms  which,  if  systemati- 
cally referable  to  the  Antilopida,  nevertheless  are  more  or  less 
clearly  transitional  between  this  and  the  family  of  the  Sheep 
22 


HISTORICAL   PALAEONTOLOGY. 


and   Goats.     Thus  the  Palceoreas  of  the  Upper  Miocene  of 
Greece  may  be  regarded  as  a  genuine  Antelope  ;    but  the 


Fig.  244. — a,  Skull  of  Hippopotamus  Sivalensis,  viewed  from  below,  one-eighth  of  the 
natural  size  ;  b,  Molar  tooth  of  the  same,  showing  the  surface  of  the  crown,  one-half  of 
the  natural  size  ;  r,  Front  of  the  lower  jaw  of  the  same,  showing  the  six  incisors  and  the 
tusk-like  canines,  one-eighth  of  the  natural  size.  Upper  Miocene,  Siwalik  Hills.  (After 
Falconer  and  Cautley.) 

Tragoceras  of  the  same  deposit  is  intermediate  in  its  characters 
between  the  typical  Antelopes  and  the  Goats.  Perhaps  the 
most  remarkable,  however,  of  these  Miocene  Ruminants  is  the 
Sivatherium  gigauteum  (fig.  245)  of  the  Siwalik  Hills,  in  India. 
In  this  extraordinary  animal  there  were  two  pairs  of  horns, 
supported  by  bony  "  horn-cores,"  so  that  there  can  be  no 
hesitation  in  referring  Sivatherium  to  the  Cavicorn  Rumin- 
ants. If  all  these  horns  had  been  simple,  there  would  have 
been  no  difficulty  in  considering  Sivatherium  as  simply  a 
gigantic  four-horned  Antelope,  essentially  similar  to  the  living 
Antilope  (Tetraceros]  quadricornis  of  India.  The  hinder  pair 
of  horns,  however,  is  not  only  much  larger  than  the  front  pair, 
but  each  possesses  two  branches  or  snags— a  peculiarity  not  to 
be  paralleled  amongst  any  existing  Antelope,  save  the  abnormal 
Prongbuck  (Antilocapra)  of  North  America.  Dr  Murie,  how- 
ejver,  in  an  admirable  memoir  on  the  structure  and  relationships 


THE   MIOCENE    PERIOD.  319 

of  Sivatherium,  has  drawn  attention  to  the  fact  that  the  Prong- 
buck  sheds  the  sheath  of  its  horns  annually,  and  has  suggested 


Fig.  245. — Skull  of  Sivatherittm  gigantett m,  reduced  in  size.     Miocene,  India. 
(After  Murie.) 

that  this  may  also  have  been  the  case  with  the  extinct  form. 
This  conjecture  is  rendered  probable,  amongst  other  reasons, 
by  the  fact  that  no  traces  of  a  horny  sheath  surrounding  the 
horn-cores  of  the  Indian  fossil  have  been  as  yet  detected. 
Upon  the  whole,  therefore,  we  may  regard  the  elephantine 
Sivatherium  as  being  most  nearly  allied  to  the  Prongbuck  of 
Western  America,  and  thus  as  belonging  to  the  family  of  the 
Antelopes. 

It  is  to  the  Miocene  period,  again,  to  which  we  must  refer 
the  first  appearance  of  the  important  order  of  the  tlephants 
and  their  allies  (Proboscideans},  all  of  which  are  characterised  by 
their  elongated  trunk-like  noses,  the  possession  of  five  toes  to 
the  foot,  the  absence  of  canine  teeth,  the  development  of  two 
or  more  of  the  incisor  teeth  into  long  tusks,  and  the  adaptation 
of  the  molar  teeth  to  a  vegetable  diet.  Only  three  generic 
groups  of  this  order  are  known — namely,  the  extinct  Deino- 
therium,  the  equally  extinct  Mastodons,  and  the  Elephants ;  and 
all  these  three  types  are  known  to  have  been  in  existence  as 


320  HISTORICAL  PALEONTOLOGY. 

early  as  the  Miocene  period,  the  first  of  them  being  exclusively 
confined  to  deposits  of  this  age.  Of  the  three,  the  genus 
Deinotherium  is  much  the  most  abnormal  in  its  characters ; 
so  much  so,  that  good  authorities  regard  it  as  really  being  one 
of  the  Sea-cows  (Sire/iia}— though  this  view  has  been  rendered 
untenable  by  the  discovery  of  limb-bones  which  can  hardly 
belong  to  any  other  animal,  and  which  are  distinctly  Probosci- 
dean in  type.  The  most  celebrated  skull  of  the  Deinothere 
(fig.  246)  is  one  which  was  exhumed  from  the  Upper  Miocene 

deposits  of  Epplesheim,in  Hesse- 
Darmstadt,  in  the  year  1836. 
This  skull  was  four  and  a  half 
feet  in  length,  and  indicated  an 
animal  larger  than  any  existing 
species  of  Elephant.  The  upper 
jaw  is  destitute  of  incisor  or 
canine  teeth,  but  is  furnished  on 
each  side  with  five  molars,  which 
are  opposed  to  a  corresponding 
series  of  grinding  teeth  in  the 
lower  jaw.  No  canines  are  pre- 
sent in  the  lower  jaw;  but  .the 
front  portion  of  the  jaw  is  ab- 
Fig.  246.  — Skull  of  Deinotherium  ruptly  bent  downwards,  and  car- 

gigantfutn,    greatly    reduced.      From         •  •>  i    vi          • 

fh?  Upper  Miocene  of  Germany.  HCS    tWO    huge    tlisk-llke     lllClSOr 

teeth,  which  are  curved  down- 
wards and  backwards,  and  the  use  of  which  is  rather  proble- 
matical. Not  only  does  the  Deinothere  occur  in  Europe,  but 
remains  belonging  to  this  genus  have  also  been  detected  in  the 
Siwalik  Hills,  in  India. 

The  true  Elephants  (Elephas]  do  not  appear  to  have  ex- 
isted during  the  Miocene  period  in  Europe,  but  several  species 
have  been  detected  in  the  Upper  Miocene  deposits  of  the 
Siwalik  Hills,  in  India.  The  fossil  forms,  though  in  all  cases 
specifically,  and  in  some  cases  even  sub-generically,  distinct, 
agree  with  those  now  in  existence  in  the  general  conformation 
of  their  skeleton,  and  in  the  principal  characters  of  their  den- 
tition. In  all,  the  canine  teeth  are  wanting  in  both  jaws ;  and 
there  are  no  incisor  teeth  in  the  lower  jaw,  whilst  there  are 
two  incisors  in  the  front  of  the  upper  jaw,  which  are  de- 
veloped into  two  huge  "  tusks."  There  are  six  molar  teeth 
on  each  side  of  both  the  upper  and  lower  jaw,  but  only 
one,  or  at  most  a  part  of  two,  is  in  actual  use  at  any  given 
time ;  and  as  this  becomes  worn  away,  it  is  pushed  forward 
and  replaced  by  its  successor  behind  it.  The  molars  are  of 


THE   MIOCENE   PERIOD. 


321 


very  large  size,  and  are  each  composed  of  a  number  of  trans- 
verse plates  of  enamel  united  together  by  ivory ;  and  by  the 


Fig.  247. — A,  Molar  tooth  of  Elepha s  plantfrons,  one- third  of  the  natural  size,  show- 
ing the  grinding  surface — from  the  Upper  Miocene  of  India ;  B,  Profile  view  of  the 
last  upper  molar  of  Mastodon  Sivalensis,  one-third  of  the  natural  size— from  the  Upper 
Miocene  of  India.  (After  Falconer.) 

process  of  mastication,  the  teeth  become  worn  down  to  a  flat 
surface,  crossed  by  the  enamel-ridges  in  varying  patterns. 
These  patterns  are  different  in  the  different  species  of  Ele- 
phants, though  constant  for  each ;  and  they  constitute  one  of 
the  most  readily  available  means  of  separating  the  fossil 
forms  from  one  another.  Of  the  seven  Miocene  Elephants 
of  India,  as  judged  by  the  characters  of  the  molar  teeth, 
two  are  allied  to  the  existing  Indian  Elephant,  one  is  related 
to  the  living  African  Elephant,  and  the  remaining  four  are  in 
some  respects  intermediate  between  the  true  Elephants  and 
the  Mastodons. 

The  Mastodons,  lastly,   though   quite    elephantine   in   their 


322  HISTORICAL  PALAEONTOLOGY. 

general  characters,  possess  molar  teeth  which  have  their  crowns 
furnished  with  conical  eminences  or  tubercles  placed  in  pairs 
(fig.  247,  B),  instead  of  having  the  approximately  flat  surface 
characteristic  of  the  grinders  of  the  Elephants.  As  in  the 
latter,  there  are  two  upper  incisor  teeth,  which  grow  perma- 
nently during  the  life  of  the  animal,  and  which  constitute  great 
tusks  ;  but  the  Mastodons,  in  addition,  often  possess  two  lower 
incisors,  which  in  some  cases  likewise  grow  into  small  tusks. 
Three  species  of  Mastodon  are  known  to  occur  in  the  Upper 
Miocene  of  the  Sivvalik  Hills  of  India  ;  and  the  Miocene  de- 
posits of  the  European  area  have  yielded  the  remains  of  four 
species,  of  which  the  best  known  are  the  M.  longirostris  and  the 
M.  angustidens. 

Whilst  herbivorous  Quadrupeds,  as  we  have  seen,  were 
extremely  abundant  during  Miocene  times,  and  often  attained 
gigantic  dimensions,  Beasts  of  Prey  (Carnivora)  were  by  no 
means  wanting,  most  of  the  principal  existing  families  of  the 
order  being  represented  in  deposits  of  this  age.  Thus,  we  find 
aquatic  Carnivores  belonging  to  both  the  living  groups  of  the 
Seals  and  Walruses  ;  true  Bears  are  wanting,  but  their  place 
is  filled  by  the  closely-allied  genus  Amphicyon,  of  which  various 
species  are  known ;  Weasels  and  Otters  were  not  unknown, 
and  the  Hyanictis  and  Iditherium  of  the  Upper  Miocene  of 
Greece  are  apparently  intermediate  between  the  Civet-cats  and 
the  Hyaenas ;  whilst  the  great  Cats  of  subsequent  periods  are 
more  than  adequately  represented  by  the  huge  "  Sabre  toothed 
Tiger  "  {Michairodus),  with  its  immense  trenchant  and  serrated 
canine  teeth. 

Amongst  the  Rodent  Mammals,  the  Miocene  rocks  have 
yielded  remains  of  Rabbits,  Porcupines  (such  as  the  Hystrix 
primigenius  of  Greece),  Beavers,  Mice,  Jerboas,  Squirrels,  and 
Marmots.  All  the  principal  living  groups  of  this  order  were 
therefore  differentiated  in  Middle  Tertiary  times. 

The  Cheiroptera  are  represented  by  small  insect-eating  Bats; 
and  the  order  of  the  Insectivorous  Mammals  is  represented  by 
Moles,  Shrew-mice,  and  Hedgehogs. 

Lastly,  the  Monkeys  (Quadrumana)  appear  to  have  existed 
during  the  Miocene  period  under  a  variety  of  forms,  remains 
of  these  animals  having  been  found  both  in  Europe  and  in 
India  ;  but  no  member  of  this  order  has  as  yet  been  detected 
in  the  Miocene  Tertiary  of  the  North  American  continent. 
Amongst  the  Old  World  Monkeys  of  the  Miocene,  the  two 
most  interesting  are  the  Pliopithecus  and  DryopitJiecus  of  France. 
The  former  of  these  (fig.  248)  is  supposed  to  have  been  most 
nearly  related  to  the  living  Scmnopithcd  of  Southern  Asia,  in 


THE   PLIOCENE    PERIOD.  323 

which  case  it  must  have  possessed  a  long  tail.     The  Mesopi- 
thecus  of  the  Upper  Miocene  of  Greece  is  also  one  of  the  lower 


Fig.  248. — Lower  jaw  of  Pliopithecus  antiqnns.     Upper  Miocene,  France. 

Monkeys,  as  it  is  most  closely  allied  to  the  existing  Macaques. 
On  the  other  hand,  the  Dryopithecus  of  the  French  Upper 
Miocene  is  referable  to  the  group  of  the  "Anthropoid  Apes/' 
and  is  most  nearly  related  to  the  Gibbons  of  the  present  day, 
in  which  the  tail  is  rudimentary  and  there  are  no  .cheek- 
pouches.  Dryopithecus  was,  also,  of  large  size,  equalling  Man 
in  stature,  and  apparently  living  amongst  the  trees  and  feed- 
ing upon  fruits. 


CHAPTER    XX. 

THE    PLIOCENE    PERIOD. 

The  highest  division  of  the  Tertiary  deposits  is  termed  the 
Pliocene  formation,  in  accordance  with  the  classification  pro- 
posed by  Sir  Charles  Lyell.  The  Pliocene  formations  contain 
from  40  to  95  per  cent  of  existing  species  of  Mollusca,  the  re- 
maindes  belonging  to  extinct  species.  They  are  divided  by  Sir 
Charles  Lyell  into  two  divisions,  the  Older  Pliocene  and  Newer 
Pliocene. 

The  Pliocene  deposits  of  Britain  occur  in  Suffolk,  and  are 
known  by  the  name  of  "  Crags,"  this  being  a  local  term  used 
for  certain  shelly  sands,  which  are  employed  in  agriculture. 
Two  of  these  Crags  are  referable  to  the  Older  Pliocene,  viz., 


324  HISTORICAL   PALEONTOLOGY. 

the  White  and  Red  Crags, — and  one  belongs  to  the  Newer 
Pliocene,  viz.,  the  Norwich  Crag. 

The  White  or  Coralline  Crag  of  Suffolk  is  the  oldest  of  the 
Pliocene  deposits  of  Britain,  and  is  an  exceedingly  local  for- 
mation, occurring  in  but  a  single  small  area,  and  having  a 
maximum  thickness  of  not  more  than  50  feet.  It  consists  of 
soft  sands,  with  occasional  intercalations  of  flaggy  limestone. 
Though  of  small  extent  and  thickness,  the  Coralline  Crag  is  of 
importance  from  the  number  of  fossils  which  it  contains.  The 
name  "  Coralline  "  is  a  misnomer ;  since  there  are  few  true 
Corals,  and  the  so-called  "Corals"  of  the  formation  are  really 
Polyzoa,  often  of  very  singular  forms.  The  shells  of  the  Coral- 
line Crag  are  mostly  such  as  inhabit  the  seas  of  temperate 
regions ;  but  there  occur  some  forms  usually  looked  upon  as 
indicating  a  warm  climate. 

The  Upper  or  Red  Crag  of  Suffolk— like  the  Coralline  Crag 
—has  a  limited  geographical  extent  and  a  small  thickness, 
rarely  exceeding  40  feet.  It  consists  of  quartzose  sands,  usu- 
ally deep  red  or  brown  in  colour,  and  charged  with  numerous 
fossils. 

Altogether  more  than  200  species  of  shells  are  known  from 
the  Red  Crag,  of  which  60  per  cent  are  referable  to  existing 
species.  The  shells  indicate,  upon  the  whole,  a  temperate  or 
even  cold  climate,  decidedly  less  warm  than  that  indicated  by 
the  organic  remains  of  the  Coralline  Crag.  It  appears,  there- 
fore, that  a  gradual  refrigeration  was  going  on  during  the 
Pliocene  period,  commencing  in  the  Coralline  Crag,  becoming 
intensified  in  the  Red  Crag,  being  still  more  severe  in  the 
Norwich  Crag,  and  finally  culminating  in  the  Arctic  cold  of  the 
Glacial  period. 

Besides  the  Mollusca,  the  Red  Crag  contains  the  ear-bones 
of  Whales,  the  teeth  of  Sharks  and  Rays,  and  remains  of  the 
Mastodon,  Rhinoceros,  and  Tapir. 

The  Newer  Pliocene  deposits  are  represented  in  Britain  by 
the  Norwich  Crag,  a  local  formation  occurring  near  Norwich. 
It  consists  of  incoherent  sands,  loams,  and  gravels,  resting  in 
detached  patches,  from  2  to  20  feet  in  thickness,  upon  an 
eroded  surface  of  Chalk.  The  Norwich  Crag  contains  a  mix- 
ture of  marine,  land,  and  fresh-water  shells,  with  remains  of 
fishes  and  bones  of  mammals;  so  that  it  must  have  been  de- 
posited as  a  local  sea-deposit  near  the  mouth  of  an  ancient 
river.  It  contains  altogether  more  than  100  marine  shells, 
of  which  89  per  cent  belong  to  existing  species.  Of  the 
Mammals,  the  two  most  important  are  an  Elephant  (Elephas 
meridional is) ,  and  the  characteristic  Pliocene  Mastodon  (M. 


THE   PLIOCENE   PERIOD.  325 

Arvcrnensis\  which  is  hitherto  the  only  Mastodon  found  in 
Britain. 

According  to  the  most  recent  views  of  high  authorities, 
certain  deposits — such  as  the  so-called  "  Bridlington  Crag  "  of 
Yorkshire,  and  the  "  Chillesford  beds  "  of  Suffolk — are  to  be 
also  included  in  the  Newer  Pliocene,  upon  the  ground  that 
they  contain  a  small  proportion  of  extinct  shells.  Our  know- 
ledge, however,  of  the  existing  Mclluscan  fauna,  is  still  so  far 
incomplete,  that  it  may  reasonably  be  doubted  if  these  sup- 
posed extinct  forms  have  actually  made  their  final  disappear- 
ance, whilst  the  strata  in  question  have  a  strong  natural  con- 
nection with  the  "  Glacial  deposits,"  as  shown  by  the  number 
of  Arctic  Mollusca  which  they  contain.  Here,  therefore,  these 
beds  will  be  included  in  the  Post-Pliocene  series,  in  spite  of 
the  fact  that  some  of  their  species  of  shells  are  not  known  to 
exist  at  the  present  day. 

The  following  are  the  more  important  Pliocene  deposits 
which  have  been  hitherto  recognised  out  of  Britain: — 

1.  In  the  neighbourhood  of  Antwerp  occur  certain  "crags," 
which  are  the  equivalent  of  the  White  and  Red  Crag  in  part. 
The  lowest  of  these  contains  less  than  50  per  cent,  and  the 
highest  60  per  cent,  of  existing  species  of  shells,  the  remainder 
being  extinct. 

2.  Bordering  the  chain  of  the  Apennines,  in  Italy,  on  both 
sides  is  a  series  of  low  hills  made  up  of  Tertiary  strata,  which 
are  known  as  the  Sub-Apennine  beds.      Part    of  these  is  of 
Miocene  age,  part  is  Older  Pliocene,  and  a  portion  is  Newer 
Pliocene.     The  Older  Pliocene  portion  of  the  Sub-Apennines 
consists  of  blue  or  brown    marls,  which    sometimes  attain  a 
thickness  of  2000  feet. 

3.  In  the  valley  of  the    Arno,  above   Florence,  are  both 
Older  and  Newer  Pliocene  strata.     The  former  consist  of  blue 
clays  and  lignites,  with  an  abundance  of  plants.     The  latter 
consist  of  sands  and  conglomerates,  with  remains  of  large  Car- 
nivorous Mammals,  Mastodon,  Elephant,  Rhinoceros,  Hippo- 
potamus, &c. 

4.  In  Sicily,  Newer  Pliocene  strata  are  probably  more  largely 
developed  than  anywhere  else  in  the  world,  rising  sometimes 
to  a  height  of  3000  feet  above  the  sea.     The  series  consists 
of  clays,  marls,  sands,  and  conglomerates,  capped  by  a  com- 
pact limestone,  which  attains  a  thickness  of  from  700  to  800 
feet.     The  fossils  of  these  beds  belong  almost  entirely  to  living 
species,  one  of  the  commonest  being  the  Great  Scallop  of  the 
Mediterranean  (Pecten  Jacolxziis). 

5.  Occupying  an  extensive  area  round  the  Caspian,  Aral, 


326  HISTORICAL   PALAEONTOLOGY. 

and  Azof  Seas,  are  Pliocene  deposits  known  as  the  "  Aralo- 
Caspian  "  beds.  The  fossils  in  these  beds  are  partly  fresh- 
water, partly  marine,  and  partly  intermediate  in  character,  and 
they  are  in  great  part  identical  with  species  now  inhabiting 
the  Caspian.  The  entire  formation  appears  to  indicate  the 
former  existence  of  a  great  sheet  of  brackish  water,  forming  an 
inland  sea,  like  the  Caspian,  but  as  large  as,  or  larger  than,  the 
Mediterranean. 

6.  In  the  United  States,  strata  of  Pliocene  age  are  found  in 
North  and  South  Carolina.  They  consist  of  sands  and  clays, 
with  numerous  fossils,  chiefly  Molluscs  and  Echinoderms. 
From  40  to  60  per  cent  of  the  fossils  belong  to  existing 
species.  On  the  Loup  Fork  of  the  river  Platte,  in  the  Upper 
Missouri  region,  are  strata  which  are  also  believed  to  be  refer- 
able to  the  Pliocene  period,  and  probably  to  its  upper  division. 
They  are  from  300  to  400  feet  thick,  and  contain  land-shells, 
with  the  bones  of  numerous  Mammals,  such  as  Camels,  Rhino- 
ceroses, Mastodons,  Elephants,  the  Horse,  Stag,  &c. 

As  regards  the  life  of  the  Pliocene  period,  there  are  only 
two  classes  of  organisms  to  which  our  attention  need  be 
directed — namely,  the  Shell-fish  and  the  Mammals.  So  far  as 
the  former  are  concerned,  we  have  to  note  in  the  first  place 
that  the  introduction  of  new  species  of  animals  upon  the  globe 
went  on  rapidly  during  this  period.  In  the  Older.  Pliocene 
deposits,  the  number  of  shells  of  existing  species  is  only  from 
40  to  60  per  cent;  but  in  the  Newer  Pliocene  the  pro- 
portion of  living  forms  rises  to  as  much  as  from  80  to 
95  per  cent.  Whilst  the  Molluscs  thus  become  rapidly  mo- 
dernised, the  Mammals  still  all  belong  to  extinct  species, 
though  modern  generic  types  gradually  supersede  the  more 
antiquated  forms  of  the  Miocene.  In  the  second  place,  there 
is  good  evidence  to  show  that  the  Pliocene  period  was  one  in 
which  the  climate  of  the  northern  hemisphere  underwent  a 
gradual  refrigeration.  In  the  Miocene  period,  there  is  evi- 
dence to  show  that  Europe  possessed  a  climate  very  similar 
to  that  now  enjoyed  by  the  Southern  United  States,  and  cer- 
tainly very  much  warmer  than  it  is  at  present.  The  presence 
of  Palm-trees  upon  the  land,  and  of  numerous  large  Cowries, 
Cones,  and  other  shells  of  warm  regions  in  the  sea,  sufficiently 
proves  this.  In  the  Older  Pliocene  deposits,  on  the  other 
hand,  northern  forms  predominate  amongst  the  Shells,  though 
some  of  the  types  of  hotter  regions  still  survive.  In  the  Newer 
Pliocene,  again,  the  Molluscs  are  such  as  almost  exclusively 
inhabit  the  seas  of  temperate  or  even  cold  regions ;  whilst  if 
we  regard  deposits  like  the  "  Bridlington  Crag  "  and  "  Chilles- 


THE   PLIOCENE   PERIOD.  327 

ford  beds "  as  truly  referable  to  this  period,  we  meet  at  the 
close  of  this  period  with  shells  such  as  nowadays  are  distinct- 
ively characteristic  of  high  latitudes.  It  might  be  thought 
that  the  occurrence  of  Quadrupeds  such  as  the  Elephant, 
Rhinoceros,  and  Hippopotamus,  would  militate  against  this 
generalisation,  and  would  rather  support  the  view  that  the 
climate  of  Europe  and  the  United  States  must  have  been  a 
hot  one  during  the  later  portion  of  the  Pliocene  period.  \Ve 
have,  however,  reason  to  believe  that  many  of  these  extinct 
Mammals  were  more  abundantly  furnished  with  hair,  and  more 
adapted  to  withstand  a  cool  temperature,  than  any  of  their 
living  congeners.  We  have  also  to  recollect  that  many  of 
these  large  herbivorous  quadrupeds  may  have  been,  and 
indeed  probably  were,  more  or  less  migratory  in  their  habits  ; 
and  that  whilst  the  winters  of  the  later  portion  of  the  Pliocene 
period  were  cold,  the  summers  might  have  been  very  hot. 
This  would  allow  of  a  northward  migration  of  such  terrestrial 
animals  during  the  summer-time,  when  there  would  be  an 
ample  supply  of  food  and  a  suitably  high  temperature,  and  a 
southward  recession  towards  the  approach  of  winter. 

The  chief  palaeontological  interests  of  the  Pliocene  deposits, 
as  of  the  succeeding  Post-Pliocene,  centre  round  the  Mammals 
of  the  period ;  and  amongst  the  many  forms  of  these  we  may 
restrict  our  attention  to  the  orders  of  the  Hoofed  Quadrupeds 
(Ungulates),  the  Proboscideans,  the  Carnivora,  and  the  Quad- 
rumana.  Almost  all  the  other  Mammalian  orders  are  more 
or  less  fully  represented  in  Pliocene  times,  but  none  of  them 
attains  any  special  interest  till  we  enter  upon  the  Post-Pliocene. 

Amongst  the  Odd-toed  Ungulates,  in  addition  to  the  remains 
of  true  Tapirs  (Tapirus  Arverncnsis],  we  meet  with  the  bones 
of  several  species  of  Rhinoceros,  of  which  the  Rhinoceros  Etrus- 
cus  and  R.  megarhinus  (fig.  249)  are  the  most  important.  The 
former  of  these  (fig.  249,  A)  derives  its  specific  name  from  its 
abundance  in  the  Pliocene  deposits  of  the  Val  d'Arno,  near 
Florence,  and  though  principally  Pliocene  in  its  distribution, 
it  survived  into  the  earlier  portion  of  the  Post-Pliocene  period. 
Rhinoceros  Etruscus  agreed  with  the  existing  African  forms  in 
having  two  horns  placed  one  behind  the  other,  the  front  one 
being  the  longest ;  but  it  was  comparatively  slight  and  slender 
in  its  build,  whilst  the  nostrils  were  separated  by  an  incom- 
plete bony  partition.  In  the  Rhinoceros  megarhinus  (fig.  249, 
B),  on  the  other  hand,  no  such  partition  exists  between  the 
nostrils,  and  the  nasal  bones  are  greatly  developed  in  size.  It 
was  a  two-horned  form,  and  is  found  associated  with  Elephas 
meridionalis  and  E.  antiquus  in  the  Pliocene  deposits  of  the 


328  -  HISTORICAL   PALEONTOLOGY. 

Val  d'Arno,  near  Florence.  Eike  the  preceding,  it  survived, 
in  diminished  numbers,  into  the  earlier  portion  of  the  Post- 
Pliocene  period. 

The  Horses  (Equida)  are  represented,  both  in  Europe  and 


Fig.  249. — A,  Under  surface  of  the  skull  of  Rhinoceros  Etrnscns,  one-seventh  of  the 
natural  size— Pliocene,  Italy  ;  B,  Crowns  of  the  three  true  molars  of  the  upper  jaw,  left 
side,  of  Rhinoceros  megarhinus  (R.  leptorhimts,  Falconer),  one-half  of  the  natural  size 
— Pliocene,  France.  (After  Falconer.) 

America,  by  the  three-toed  Hipparions,  which  survive  from  the 
Miocene,  but  are  now  verging  upon  extinction.  For  the  first 
time,  also,  we  meet  with  genuine  Horses  (Equus),  in  which 
each  foot  is  provided  with  a  single  complete  toe  only,  encased 
in  a  single  broad  hoof.  One  of  the  American  species  of  this 
period  (the  Equus  excelsus]  quite  equalled  the  modern  Horse 
in  stature  ;  and  it  is  interesting  to  note  the  occurrence  of  indi- 
genous horses  in  America  at  such  a  comparatively  late  geo- 
logical epoch,  seeing  that  this  continent  certainly  possessed 
none  of  these  animals  when  first  discovered  by  the  Spaniards. 
Amongst  the  Even-toed  Ungulates,  we  may  note  the  occur- 


THE   PLIOCENE   PERIOD.  329 

rence  of  Swine  (Suida),  of  forms  allied  to  the  Camels  (Camel- 
idte),  and  of  various  kinds  of  Deer  (Ccnnda)\  but  the  most 
interesting  Pliocene  Mammal  belonging  to  this  section  is  the 
great  Hippopotamus  major  of  Britain  and  Europe.  This  .well- 
known  species  is  very  closely  allied  to  the  living  Hippopotamus 
amphibius  of  Africa,  from  which  it  is  separated  only  by  its 
larger  dimensions,  and  by  certain  points  connected  with  the 
conformation  of  the  skeleton.  It  is  found  very  abundantly  in 
the  Pliocene  deposits  of  Italy  and  France,  associated  with  the 
remains  of  the  Elephant,  Mastodon,  and  Rhinoceros,  and  it 
survived  into  the  earlier  portion  of  the  Post-Pliocene  period. 
During  this  last-mentioned  period,  it  extended  its  range  north- 
wards, and  is  found  associated  with  the  Reindeer,  the  Bison, 
and  other  northern  animals.  From  this  fact  it  has  been  infer- 
red, with  great  probability,  that  the  Hippopotamus  major  was 
furnished  with  a  long  coat  of  hair  and  fur,  thus  differing  from 
its  nearly  hairless  modern  representative,  and  resembling  its 
associates,  the  Mammoth  and  the  Woolly  Rhinoceros. 

Passing  on  to  the  Pliocene  Proboscideans,  we  find  that  the 
great  Deinotheria  of  the  Miocene  have  now  wholly  disappeared, 
and  the  sole  representatives  of  the  order  are  Mastodons  and 
Elephants.  The  most  important  member  of  the  former  group 
is  the  Mastodon  Arvernensis  (fig.  250),  which  ranged  widely 


Fig.  250.— Third  milk-molar  of  the  left  side  of  the  upper  jaw  of  Mastodon 
Arveruensis,  showing  the  grinding  surface.     Pliocene. 

over  Southern  Europe  and  England,  being  generally  associated 
with  remains  of  the  Elephas  meridionalis,  E.  antiquus,  Rhino- 
ceros megarhinus,  and  Hippopotamus  major.  The  lower  jaw 
seems  to  have  been  destitute  of  incisor  teeth ;  but  the  upper 
incisors  are  developed  into  great  tusks,  which  sometimes  reach 


330  HISTORICAL   PALEONTOLOGY. 

a  length  of  nine  feet,  and  which  have  the  simple  curvature  of 
the  tusks  of  the  existing  Elephants.  Amongst  the  Pliocene 
Elephants  the  two  most  important  are  the  Elephas  meridionalis 
and  the  Elephas  antiquus.  Of  these,  the  Elephas  meridionalis 
(fig.  251)  is  found  abundantly  in  the  Pliocene  deposits  of 


Fig.  251.  —  Molar  tooth  of  Elephas  meridionalis,  one-third  of  the  natural  size. 
Pliocene  and  Post-Pliocene. 

Southern  Europe  and  England,  and  also  survived  into  the 
earlier  portion  of  the  Post- Pliocene  period.  Its  molar  teeth 
are  of  the  type  of  those  of  the  existing  African  Elephant,  the 
spaces  enclosed  by  the  transverse  enamel-plates  being  more 
or  less  lozenge-shaped,  whilst  the  curvature  of  the  tusks  is 
simple.  The  Elephas  antiqmis  (fig.  252)  is  very  generally 


Fig.  252. — Molar  tooth  of  Elephas  antignns,  one-third  of  the  natural  size. 
Pliocene  and  Post-Pliocene. 

associated  with  the  preceding,  and  it  survived  to  an  even 
later  stage  of  the  Post-Pliocene  period.  The  molar  teeth  are 
of  the  type  of  the  existing  Indian  Elephant,  with  compara- 
tively thin  enamel-ridges,  placed  closer  together  than  in  the 
African  type  ;  whilst  the  tusks  were  nearly  straight. 

Amongst  the  Pliocene  Carnivores,  we  meet  with  true  Bears 
( Ursus  An>ernensis],  Hyaenas  (such  as  Hycena  Hipparionum], 
and  genuine  Lions  (such  as  the  Felis  angttslus  of  North 
America);  but  the  most  remarkable  of  the  beasts  of  prey  of 


THE   PLIOCENE  PERIOD. 


331 


this  period  is  the  great  "  Sabre-toothed  Tiger  "  (Machairodus), 
species  of  which  existed  in  the  earlier  Miocene,  and  survived 
to  the  later  Post-Pliocene.  In  this  remarkable  form  we  are 
presented  with  perhaps  the  most  highly  carnivorous  type  of 
all  known  beasts  of  prey.  Not  only  aie  the  jaws  shorter  in 
proportion  even  than  those  of  the  great  Cats  of  the  present 
day,  but  the  canine  teeth  (fig.  253)  are  of  enormous  size, 


Fig.   253. — A,   Skull  of  Machairodns  cultridens,  without  the  lower  jaw,  reduced  in 
size  ;  B,  Canine  tooth  of  the  same,  one-half  the  natural  size.     Pliocene,  France. 

greatly  flattened  so  as  to  assume  the  form  of  a  poignard,  and 
having  their  margins  finely  serrated.  Apart  from  the  charac- 
ters of  the  skull,  the  remainder  of  the  skeleton,  so  far  as  known, 
exhibits  proofs  that  the  Sabre-toothed  Tiger  was  extraordi- 
narily muscular  and  powerful,  and  in  the  highest  degree  adapt- 
ed for  a  life  of  rapine.  Species  of  Machairodns  must  have 
been  as  lafrge  as  the  existing  Lion ;  and  the  genus  is  not  only 
European,  but  is  represented  both 'in  South  America  and  in 
India,  so  that  the  geographical  range  of  these  predaceoi»s 
beasts  must  have  been  very  extensive. 

Lastly,  we  may  note  that  the  Pliocene  deposits  of  Europe 
have  yielded  the  remains  of  Monkeys  {Quadrnmana\  allied  to 
the  existing  Semnopitkeci  and  Macaques. 


332  HISTORICAL   PALEONTOLOGY. 


LITERATURE. 

The  following  list  comprises  a  small  selection  of  some  of  the  more  im- 
portant and  readily  accessible  works  and  memoirs  relating  to  the  Tertiary 
rocks  and  their  fossils.  With  few  exceptions,  foreign  works  relating  to 
the  Tertiary  strata  of  the  continent  of  Europe  or  their  organic  remains 
have  been  omitted  : — 

(1)  '  Elements  of  Geology. '     Lyell. 

(2)  '  Students'  Elements  of  Geology.'     Lyell. 

(3)  '  Manual  of  Palaeontology.'     Owen. 

(4)  'British  Fossil  Mammals  and  Birds.'     Owen. 

(5)  'Traite  de  Paleontologie.'     Pictet. 

(6)  '  Cours  Elemenlaire  de  Paleontologie. '     D'Orbigny. 

(7)  "Probable  Age  of  the  London  Clay,"  &c. — 'Quart.  Journ.  Geol. 

Soc.,'  vol.  iii.     Prestwich. 

(8)  'Structure  and  Probable  Age  of  the  Bagshot  Sands' — Ibid.,  vol.  iii. 

Prestwich. 

(9)  '  Tertiary  Formations  of  the  Isle  of  Wight ' — Ibid.,  vol.  ii.     Prest- 

wich. 

(10)  'Structure  of  the  Strata  between  the  London  Clay  and  the  Chalk,' 

&c. — Ibid.,  vols.  vi.,  viii.,  and  x.     Prestwich. 

(11)  'Correlation   of  the   Eocene  Tertiaries  of   England,   France,   and 

Belgium' — Ibid.,  vol.  xxvii.      Prestwich. 

(12)  'On  the  Fluvio-marine  Formations  of  the  Isle  of  Wight ' — Ibid., 

vol.  ix.     Edward  Forbes. 

(13)  'Newer  Tertiary  Deposits  of  the  Sussex  Coast '—Ibid.,  vol.  xiii. 

Godwin-Austen. 

(14)  'Kainozoic   Formations  of  Belgium' — Ibid.,  vol.  xxii.     Godwin- 

Austen. 

(15)  'Tertiary  Strata  of  Belgium  and  French  Flanders' — Ibid.,  vol.  viii. 

Lyell. 

(16)  'On  Tertiary  Leaf-beds  in  the  Isle  of  Mull'— Ibid.,  vol.  vii.     The 

Duke  of  Argyll. 

(17)  'Newer  Tertiaries  of  Suffolk  and  their  Fauna' — Ibid.,  vol.  xxvi. 

Ray  Lankester. 

(18)  '  Lower  London  Tertiaries  of  Kent ' — Ibid.,  vol.  xxii.     Whitaker. 

(19)  "Guide   to   the   Geology   of    London" — 'Mem.    Geol.    Survey.' 

Whitaker. 

(20)  '  Memoirs  of  the  Geological  Survey  of  Great  Britain.' 

(21)  'Introductory  Outline  of  the  Geology  of  the  Crag  District'  (Sup- 

plement to  Crag  Mollusca,  Palrcontographical  Society).  S.  V. 
Wood,  jun.,  and  F.  W.  Harmer.  , 

(22)  "Tertiary  Fluvio-marine  Deposits  of  the  Isle  of  Wight."     Edward 

Forbes.  Edited  by  Godwin- Austen  ;  with  Descriptions  of  the 
Fossils  by  Morris,  Salter,  and  Rupert  Jones — '  Memoirs  of  the 
Geological  Survey.' 

(23)  'Geological  Excursions  round  the  Isle  of  Wight.'     Mantell. 

(24)  'Catalogue  of  British  Fossils.'     Morris. 

(25)  'Catalogue  of  Fossils  in  the  Museum  of  Practical  Geology.'     Ethe- 

ridge. 

(26)  'Monograph  of  the  Crag  Polyzoa'  (Palaeontographical  Society).   Busk. 

(27)  'Monograph  of  the  Tertiary  Brachiopoda  '  (Ibid.)     Davidson. 

(28)  'Monograph   of    the   Tertiary   Malacostracous    Crustacea'  (Ibid.) 

Bell. 


THE   PLIOCENE   PERIOD.  333 

(29)  'Monograph  of  the  Tertiary  Corals'  (Ibid.)     Milne-Edwards  and 

Haime. 

(30)  '  Supplement  to  the  Tertiary  Corals  '  (Ibid.)     Martin  Duncan. 

(31)  'Monograph  of  the  Eocene  Mollusca  '  (Ibid.)     Fred.  E.  Edwards. 

(32)  'Monograph  of  the  Eocene  Mollusca  '  (Ibid.)     Searles  V.  Wood. 

(33)  'Monograph  of  the  Crag  Mollusca '  (Ibid.)     Searles  V.  Wood. 

(34)  'Monograph  of  the  Tertiary  Entomostraca '  (Ibid.)     Rupert  Jones. 

(35)  '  Monograph  of  the  P'oraminifera  of  the  Crag'  (Ibid.)     Rupert  Jones, 

Parker,  and  H.  B.  Brady. 

(36)  'Monograph  of  the  Radiaria  of  the  London  Clay  '  (Ibid.)     Edward 

Forbes. 

(37)  'Monograph  of  the  Cetacea  of  the  Red  Crag  '  (Ibid.)     Owen. 

(38)  'Monograph  of  the  Fossil  Reptiles  of  the  London  Clay'  (Ibid.) 

Owen  and  Bell. 

(39)  "On  the  Skull  of  a  Dentigerous  Bird  from  the  London  Clay  of 

Sheppey"— 'Quart.  Journ.  Geol.  Soc.,' vol.  xxix.     Owen. 

(40)  '  Ossemens  Fossiles.'     Cuvier. 

(41)  'Fauna  Antiqua  Sivalensis. '     Falconer  and  Sir  Proby  Cautley. 

(42)  '  Palsjontological  Memoirs.'     Falconer. 

(43)  'Animaux  Fossiles  et  Geologic  de  FAttique.'     Gaudry. 

(44)  "Principal  Characters  of  the  Dinocerata" — 'American  Journ.   of 

Science  and  Arts,'  vol.  xi.     Marsh. 

(45)  'Principal  Characters  of  the  Brontotheridae  '  (Ibid.)     Marsh. 

(46)  'Principal  Characters  of  the  Tillodontia  '  (Ibid.)     Marsh. 

(47)  "Extinct  Vertebrata  of  the  Eocene  of  Wyoming" — 'Geological 

Survey  of  Montana,' &c.,  1872.     Cope. 

(48)  "Ancient   Fauna   of  Nebraska" — 'Smithsonian  Contributions   to 

Knowledge,'  vol.  vi.     Leidy. 

(49)  '  Manual  of  Geology. '     Dana. 

(50)  "Palaeontology    and     Evolution"     (Presidential    Address    to    the 

Geological   Society  of  London,    1870)— 'Quart.    Journ.    Geol. 
Soc.,'  vol.  xxvi.     Huxley. 

(51)  '  Mineral  Conchology. '     Sowerby. 

(52)  'Description  des  Coquilles  Fossiles,'  &c.     Deshayes. 

(53)  '  Description  des  Coquilles  Tertiaires  de  Belgique.'     Nyst. 

(54)  '  Fossilen  Polypen  des  Wiener  Tertiar-beckens.'     Reuss. 

(55)  'Palseontologische  Studien  iiber  die   alteren  Tertiar-schichten  der 

Alpen.'     Reuss. 

(56)  'Land  und  Siiss-wasser  Conchylien  der  Vorwelt.'     Sandberger. 

(57)  'Flora  Tertiaria  Helvetica.'     Heer. 

(58)  '  Flora  Fossilis  Arctica. '     Heer. 

(59)  '  Recherches  sur  le  Climat  et  la  Vegetation  du  Pays  Tertiaire. '    Heer. 

(60)  'Fossil  Flora  of  Great  Britain.'     Lindley  and  Hutton. 

(61)  *  Fossil  Fruits  and  Seeds  of  the  London  Clay.'     Bowerbank. 

(62)  "Tertiary  Leaf-beds  of  the  Isle  of  Mull"— 'Quart.  Journ.    Geol. 

Soc.,'  vol.  vii.     Edward  Forbes. 

(63)  'The  Geology  of  England  and  Wales.'     Horace  B.  Woodward.* 

*  This  work — published  whilst  these  sheets  were  going  through  the  press — gives  to  the 
Student  a  detailed  view  of  all  the  strata  of  England  and  Wales,  with  their  various  sub- 
divisions, from  the  base  of  the  Palaeozoic  to  the  top  of  the  Tertiary. 


23 


334  HISTORICAL  PALEONTOLOGY. 

CHAPTER    XXI. 

THE    QUATERNARY    PERIOD. 

THE  POST-PLIOCENE  PERIOD. 

Later  than  any  of  the  Tertiary  formations  are  various  de- 
tached and  more  or  less  superficial  accumulations,  which  are 
generally  spoken  of  as  the  Post- Tertiary  formations,  in  accord- 
ance with  the  nomenclature  of  Sir  Charles  Lyell — or  as  the 
Quaternary  formations,  in  accordance  with  the  general  usage 
of  Continental  geologists.  In  all  these  formations  we  meet 
with  no  Mollusca  except  such  as  are  now  alive — with  the 
partial  and  very  limited  exception  of  some  of  the  oldest  de- 
posits of  this  period,  in  which  a  few  of  the  shells  occasionally 
belong  to  species  not  known  to  be  in  existence  at  the  pre- 
sent day.  Whilst  the  Shell-fish  of  the  Quaternary  deposits  are, 
generally  speaking,  identical  with  existing  forms,  the  Mammals 
are  sometimes  referable  to  living,  sometimes  to  extinct  species. 
In  accordance  with  this,  the  Quaternary  formations  are  divided 
into  two  groups  :  (i)  The  Post- Pliocene,  in  which  the  shells  are 
almost  invariably  referable  to  existing  species,  but  some  of  the 
Mammals  are  extinct ;  and  (2)  the  Recent,  in  which  the  shells 
and  the  Mammals  alike  belong  to  existing  species.  The  Post- 
Pliocene  deposits  are  often  spoken  of  as  the  Pleistocene  forma- 
tions (Gr.  pleistos,  most;  kainos,  new  or  recent),  in  allusion  to 
the  fact  that  the  great  majority  of  the  living  beings  of  this 
period  belong  to  the  species  characteristic  of  the  "  new  "  or 
Recent  period. 

The  Recent  deposits,  though  of  the  highest  possible  interest, 
do  not  properly  concern  the  palaeontologist  strictly  so-called, 
but  the  zoologist,  since  they  contain  the  remains  of  none  but 
existing  animals.  They  are  "  Pre-historic,"  but  they  belong 
entirely  to  the  existing  terrestrial  order.  The  Post '-  Pliocene 
deposits,  on  the  other  hand,  contain  the  remains  of  various 
extinct  Mammals  ;  and  though  Man  undoubtedly  existed  in, 
at  any  rate,  the  later  portion  of  this  period,  if  not  through- 
out the  whole  of  it,  they  properly  form  part  of  the  domain  of 
the  palaeontologist. 

The  Post-Pliocene  deposits  are  extremely  varied,  and  very 
widely  distributed  ;  and  owing  to  the  mode  of  their  occurrence, 
the  ordinary  geological  tests  of  age  are  in  their  case  but  very 
partially  available.  The  subject  of  the  classification  of  these 


THE   QUATERNARY    PERIOD.  335 

deposits  is  therefore  an  extremely  complicated  one  ;  and  as 
regards  the  age  of  even  some  of  the  most  important  of  them, 
there  still  exists  considerable  difference  of  opinion.  For  our 
present  purpose,  it  will  be  convenient  to  adopt  a  classifica- 
tion of  the  Post-Pliocene  deposits  founded  on  the  relations 
which  they  bear  in  time  to  the  great  "  Ice-age  "  or  "  Glacial 
period;"  though  it  is  not  pretended  that  our  present  know- 
ledge is  sufficient  to  render  such  a  classification  more  than  a 
provisional  one. 

In  the  early  Tertiary  period,  as  we  have  seen,  the  climate  of 
the  northern  hemisphere,  as  shown  by  the  Eocene  animals  and 
plants,  was  very  much  hotter  than  it  is  at  present — partaking, 
indeed,  of  a  sub-tropical  character.  In  the  Middle  Tertiary  or 
Miocene  period,  the  temperature,  though  not  so  high,  was  still 
much  warmer  than  that  now  enjoyed  by  the  northern  hemi- 
sphere ;  and  we  know  that  the  plants  of  temperate  regions  at 
this  time  flourished  within  the  Arctic  circle.  In  the  later 
Tertiary  or  Pliocene  period,  again,  there  is  evidence  that  the 
northern  hemisphere  underwent  a  further  progressive  diminu- 
tion of  temperature  ;  though  the  climate  of  Europe  generally 
seems  at  the  close  of  the  Tertiary  period  to  have  been  if  any- 
thing warmer,  or  at  any  rate  not  colder,  than  it  is  at  the  present 
day.  With  the  commencement  of  the  Quaternary  period, 
however,  this  diminution  of  temperature  became  more  de- 
cided ;  and  beginning  with  a  temperate  climate,  we  find  the 
greater  portion  of  the  northern  hemisphere  to  become  gradu- 
ally subjected  to  all  the  rigours  of  intense  Arctic  cold.  All 
the  mountainous  regions  of  Northern  and  Central  Europe,  of 
Britain,  and  of  North  America,  became  the  nurseries  of  huge 
ice-streams,  and  large  areas  of  the  land  appear  to  have  been 
covered  with  a  continuous  ice-sheet.  The  Arctic  conditions  of 
this,  the  well-known  "  Glacial  period,"  relaxed  more  than  once, 
and  were  more  than  once  re-established  with  lesser  intensity. 
Finally,  a  gradual  but  steadily  progressive  amelioration  of  tem- 
perature took  place ;  the  ice  slowly  gave  way,  and  ultimately 
disappeared  altogether ;  and  the  climate  once  more  became 
temperate,  except  in  high  northern  latitudes. 

The  changes  of  temperature  sketched  out  above  took  place 
slowly  and  gradually,  and  occupied  the  whole  of  the  Post- 
Pliocene  period.  In  each  of  the  three  periods  marked  out  by 
these  changes — in  the  early  temperate,  the  central  cold,  and 
the  later  temperate  period — certain  deposits  were  laid  down 
over  the  surface  of  the  northern  hemisphere ;  and  these  de- 
posits collectively  constitute  the  Post- Pliocene  formations. 
Hence  we  may  conveniently  classify  all  the  accumulations  of 


336  HISTORICAL   PALEONTOLOGY. 

this  age  under  the  heads  of  (i)  Pre- Glacial  deposits,  (2)  Glacial 
deposits,  and  (3)  Post-Glacial  deposits,  according  as  they  were 
formed  before,  during,  or  after  the  "  Glacial  period."  It  can- 
not by  any  means  be  asserted  that  we  can  definitely  fix  the 
precise  relations  in  time  of  all  the  Post-Pliocene  deposits  to  the 
Glacial  period.  On  the  contrary,  there  are  some  which  hold  a 
very  disputed  position  as  regards  this  point;  and  there  are 
others  which  do  not  admit  of  definite  allocation  in  this  manner 
at  all,  in  consequence  of  their  occurrence  in  regions  where  no 
"Glacial  Period"  is  known  to  have  been  established.  For 
our  present  purpose,  however,  dealing  as  we  shall  have  to  do 
principally  With  the  northern  hemisphere,  the  above  classifi- 
cation, with  all  its  defects,  has  greater  advantages  than  any 
other  that  has  been  yet  proposed. 

I.  PRE-GLACIAL  DEPOSITS. — The  chief  pre  glacial  deposit  of 
Britain  is  found  on  the  Norfolk  coast,  reposing  upon  the  Newer 
Pliocene  (Norwich  Crag),  and  consists  of  an  ancient  land-sur- 
face which  is  known  as  the  "  Cromer  Forest-bed. " 

This  consists  of  an  ancient  soil,  having  embedded  in  it  the 
stumps  of  many  trees,  still  in  an  erect  position,  with  remains 
of  living  plants,  and  the  bones  of  recent  and  extinct  quadru- 
peds. It  is  overlaid  by  fresh-water  and  marine  beds,  all  the 
shells  of  which  belong  to  existing  species,  and  it  is  finally  sur- 
mounted by  true  "glacial  drift/'  While  all  the  shells  and 
plants  of  the  Cromer  Forest-bed  and  its  associated  strata  belong 
to  existing  species,  the  Mammals  are  partly  living,  partly  ex- 
tinct. Thus  we  find  the  existing  Wolf  (Cam's  lupus),  Red 
Deer  (Cervus  claphus),  Roebuck  (Cerrus  capreolus),  Mole 
(Talpa  Europ&a),  and  Beaver  (Castor  fiber),  living  in  western 
England  side  by  side  with  the  Hippopotamus  major,  Elephas 
antiquus,  Elephas  meridionalis,  Rhinoceros  Etruscus,  and  R. 
megarhinus  of  the  Pliocene  period,  which  are  not  only  extinct, 
but  imply  an  at  any  rate  moderately  warm  climate.  Besides 
the  above,  the  Forest-bed  has  yielded  the  remains  of  several 
extinct  species  of  Deer,  of  the  great  extinct  Beaver  (Trogon- 
therium  Cuvieri),  of  the  Caledonian  Bull  or  "  Urus "  (Bos 
primigenius],  and  of  a  Horse  (Equus  fossilis),  little  if  at  all 
distinguishable  from  the  existing  form. 

The  so-called  "  Bridlington  Crag  "  of  Yorkshire,  and  the 
"  Chillesford  Beds  "  of  Suffolk,  are  probably  to  be  regarded  as 
also  belonging  to  this  period;  though  many  of  the  shells  which 
they  contain  are  of  an  Arctic  character,  and  would  indicate 
that  they  were  deposited  in  the  commencement  of  the  Glacial 
period  itself.  Owing,  however,  to  the  fact  that  a  few  of  the 
shells  of  these  deposits  are  not  known  to  occur  in  a  living  con- 


THE   QUATERNARY   PERIOD.  337 

dition,  these,  and  some  other  similar  accumulations,  are  some- 
times considered  as  referable  to  the  Pliocene  period. 

II.  GLACIAL  DEPOSITS.  —  Under  this  head  is  included  a 
great  series  of  deposits  which  are  widely  spread  over  both 
Europe  and  America,  and  which  were  formed  at  a  time  when 
the  climate  of  these  countries  was  very  much  colder  than  it  is 
at  present,  and  approached  more  or  less  closely  to  what  we  see 
at  the  present  day  in  the  Arctic  regions.  These  deposits  are 
known  by  the  general  name  of  the  Glacial  deposits,  or  by  the 
more  specialised  names  of  the  Drift,  the  Northern  Drift,  the 
Boulder-clay,  the  Till,  &c. 

These  glacial  deposits  are  found  in  Britain  as  far  south  as 
the  Thames,  over  the  whole  of  Northern  Europe,  in  all  the 
more  elevated  portions  of  Southern  and  Central  Europe,  and 
over  the  whole  of  North  America,  as  far  south  as  the  39th 
parallel.  They,  generally  occur  as  sands,  clays,  and  gravels, 
spread  in  widely-extended  sheets  over  all  the  geological  forma- 
tions alike,  except  the  most  recent,  and  are  commonly  spoken 
of  under  the  general  term  of  "  Glacial  drift."  They  vary  much 
in  their  exact  nature  in  different  districts,  but  they  universally 
consist  of  one,  or  all,  of  the  following  members  : — 

1.  Unstratified  clays,  or  loams,  containing  numerous  angular 
or  sub-angular  blocks  of  stone,  which  have  often  been  trans- 
ported for  a  greater  or  less  distance  from  their  parent  rock, 
and  which  often  exhibit  polished,  grooved,  or  striated  surfaces. 
These  beds  are  what  is  called  Boulder-day,  or  Till. 

2.  Sands,  gravels,  and  clays,  often  more  or  less  regularly 
stratified,  but  containing  erratic  blocks,  often  of  large  size,  and 
with  their  edges  unworn,  derived  from  considerable  distances 
from  the  place  where  they  are  now  found.     In  these  beds  it  is 
not  at  all  uncommon  to  find  fossil  shells;  and  these,  though  of 
existing  species,  are  generally  of  an  Arctic  character,  compris- 
ing a  greater  or  less  number  of  forms  which  are  now  exclusively 
found  in  the  icy  waters  of  the  Arctic  seas.     These  beds  are 
often  spoken  of  as  "  Stratified  Drift." 

3.  Stratified  sands    and   gravels,  in  which  the  pebbles  are 
worn  and  rounded,  and  which  have  been  produced  by  a  re- 
arrangement of  ordinary  glacial  beds  by  the  sea.     These  beds 
are  commonly  known  as    "  Drift-gravels,"   or    "  Regenerated 
Drift." 

Some  of  the  last-mentioned  of  these  are  doubtless  post- 
glacial ;  but,  in  the  absence  of  fossils,  it  is  often  impossible  to 
arrive  at  a  positive  opinion  as  to  the  precise  age  of  superficial 
accumulations  of  this  nature.  It  is  also  the  opinion  of  high 
authorities  that  a  considerable  number  of  the  so-called  "  cave- 


338  HISTORICAL   PALEONTOLOGY. 

deposits,"  with  the  bones  of  extinct  Mammals,  truly  belong  to 
the  Glacial  period,  being  formed  during  warm  intervals  when 
the  severity  of  the  Arctic  cold  had  become  relaxed.  It  is 
further  believed  that  some,  at  any  rate,  of  the  so-called  "  high- 
level  "  river-gravels  and  "  brick-earths  "  have  likewise  been 
deposited  during  mild  or  warm  intervals  in  the  great  age  of 
ice  ;  and  in  two  or  three  instances  this  has  apparently  been 
demonstrated — deposits  of  this  nature,  with  the  bones  of  ex- 
tinct animals  and  the  implements  of  man,  having  been  shown 
to  be  overlaid  by  true  Boulder-clay. 

The  fossils  of  the  undoubted  Glacial  deposits  are  principally 
shells,  which  are  found  in  great  numbers  in  certain  localities, 
sometimes  with  Foraminifera,  the  bivalved  cases  of  Ostracode 
Crustaceans,  &c.  Whilst  some  of  the  shells  of  the  "  Drift" 
are  such  as  now  live  in  the  seas  of  temperate  regions,  others, 
as  previously  remarked,  are  such  as  are  now  only  known  to 
live  in  the  seas  of  high  latitudes  ;  and  these  therefore  afford 
unquestionable  evidence  of  cold  conditions.  Amongst  these 
Arctic  forms  of  shells  which  characterise  the  Glacial  beds 
may  be  mentioned  Pecten  Islandicus  (fig.  254),  Pecten  Groen- 


Fig.  254. — Left  valve  of  Pecten  Islandicus.     Glacial  and  Recent. 

la?idicus,  Scalaria  Grcenlandica,  Leda  truncata,  Astarte  borealis, 
Tellina  proximo,,  Natica  clausa,  &c. 

III.  POST-GLACIAL  DEPOSITS. — As  the  intense  cold  of  the 
Glacial  period  became   gradually   mitigated,    and    temperate 


THE   QUATERNARY   PERIOD.  339 

conditions  of  climate  were  once  more  re-established,  various 
deposits  were  formed  in  the  northern  hemisphere,  which  are 
found  to  contain  the  remains  of  extinct  Mammals,  and  which, 
therefore,  are  clearly  of  Post-Pliocene  age.  To  these  deposits 
the  general  name  of  Post-Glacial  formations  is  given  ;  but  it  is 
obvious  that,  from  the  nature  of  the  case,  and  with  our  present 
limited  knowledge,  we  cannot  draw  a  rigid  line  of  demarcation 
between  the  deposits  formed  towards  the  close  of  the  Glacial 
period,  or  during  warm  "  interglacial "  periods,  and  those  laid 
down  after  the  ice  had  fairly  disappeared.  Indeed  it  is  ex- 
tremely improbable  that  any  such  rigid  line  of  demarcation 
should  ever  have  existed ;  and  it  is  far  more  likely  that  the 
Glacial  and  Post-Glacial  periods,  and  their  corresponding  de- 
posits, shade  into  one  another  by  an  imperceptible  gradation. 
Accepting  this  reservation,  we  may  group  together,  under  the 
general  head  of  "  Post-Glacial  Deposits,*'  most  of  the  so-called 
"  Valley  -  gravels,"  "  Brick  -  earths,"  and  "  Cave  -  deposits,"  to- 
gether with  some  "raised  beaches"  and  various  deposits  of 
peat.  Though  not  strictly  within  the  compass  of  this  work, 
a  few  words  may  be  said  here  as  to  the  origin  and  mode 
of  formation  of  the  Brick-earths,  Valley-gravels,  and  Cave- 
deposits,  as  the  subject  will  thus  be  rendered  more  clearly 
intelligible. 

Every  river  produces  at  the  present  day  beds  of  fine  mud 
and  loam,  and  accumulations  of  gravel,  which  it  deposits  at 
various  parts  of  its  course — the  gravel  generally  occupying  the 
lowest  position,  and  the  finer  sands  and  mud  coming  above. 
Numerous  deposits  of  a  similar  nature  are  found  in  most 
countries  in  various  localities,  and  at  various  heights  above 
the  present  channels  of  our  rivers.  Many  of  these  fluviatile 
(L&l.fluvius,  a  river)  deposits  consist  of  fine  loam,  worked  for 
brick-making,  and  known  as  "  Brick-earths ;"  and  they  have 
yielded  the  remains  of  numerous  extinct  Mammals,  of  which 
the  Mammoth  (Elephas  primigenius)  is  the  most  abundant. 
In  the  valley  of  the  Rhine  these  fluviatile  loams  (known  as 
"  Loess  ")  attain  a  thickness  of  several  hundred  feet,  and  con- 
tain land  and  fresh-water  shells  of  existing  species.  With 
these  occur  the  remains  of  Mammals,  such  as  the  Mammoth 
and  Woolly  Rhinoceros.  Many  of  these  Brick -earths  are 
undoubtedly  Post-Glacial,  but  others  seem  to  be  clearly  "inter- 
glacial  ; "  and  instances  have  recently  been  brought  forward  in 
which  deposits  of  Brick-earth  containing  bones  and  shells  of 
fresh-water  Molluscs  have  been  found  to  be  overlaid  by  regu- 
lar unstratified  boulder-clay. 

The  so-called  "Valley-gravels,"  like  the  Brick-earths,  are 


340 


HISTORICAL    PALAEONTOLOGY. 


fluviatile  deposits,  but  are  of  a  coarser  nature,  consisting  of 
sands  and  gravels.  Every  river  gives  origin  to  deposits  of 
this  kind  at  different  points  along  the  course  of  its  valley ; 
and  it  is  not  uncommon  to  find  that  there  exist  in  the  valley 
of  a  single  river  two  or  more  sets  of  these  gravel-beds,  formed 
by  the  river  itself,  but  formed  at  times  when  the  river  ran 
at  different  levels,  and  therefore  formed  at  different  periods. 
These  different  accumulations  are  known  as  the  "  high-level " 
and  "  low-level "  gravels ;  and  a  reference  to  the  accompany- 
ing diagram  will  explain  the  origin  and  nature  of  these  de- 
posits (fig.  255).  When  a  river  begins  to  occupy  a  particular 


Fig.  255. — Recent  and  Post-Pliocene  Alluvial  Deposits,  i,  Peat  of  the  recent  period  ; 
2,  Gravel  of  the  modern  river;  2',  Loam  of  the  modern  river;  3,  Lower-level  valley- 
gravel  with  bones  of  extinct  Mammals  (Post-Pliocene)  ;  3',  Loam  of  the  same  age  as  3  ; 
4,  Higher-level  valley-gravel  (Post-Pliocene) ;  4',  Loam  of  the  same  age  as  4  ;  5,  Upland 
gravels  of  various  kinds  (often  glacial  drift)  ;  6,  Older  rock;.  (After  Sir  Charles  Lyell.) 

line  of  drainage,  and  to  form  its  own  channel,  it  will  deposit 
fluviatile  sands  and  gravels  along  its  sides.  .  As  it  goes  on 
deepening  the  bed  or  valley  through  which  it  flows,  it  will 
deposit  other  fluviatile  strata  at  a  lower  level  beside  its  new 
bed.  In  this  way  have  arisen  the  terms  "  high-level "  and 
"  low-level "  gravels.  We  find,  for  instance,  a  modern  river 
flowing  through  a  valley  which  it  has  to  a  great  extent  or 
entirely  formed  itself;  by  the  side  of  its  immediate  channel 
we  may  find  gravels,  sand,  and  loam  (fig.  255,  2  2')  deposited 
by  the  river  flowing  in  its  present  bed.  These  are  recent 
fluviatile  or  alluvial  deposits.  At  some  distance  from  the 
present  bed  of  the  river,  and  at  a  higher  level,  we  may  find 
other  sands  and  gravels,  quite  like  the  recent  ones  in  charac- 
ter and  origin,  but  formed  at  a  time  when  the  stream  flowed 
at  a  higher  level,  and  before  it  had  excavated  its  valley  to  its 
present  depth.  These  (fig.  255,  3  3')  are  the  so-called  "low- 
level  gravels "  of  a  river.  At  a  still  higher  level,  and  still 
farther  removed  from  the  present  bed  of  the  river,  we  may 
find  another  terrace,  composed  of  just  the  same  materials  as 
the  lower  one,  but  formed  at  a  still  earlier  period,  when  the 


THE  QUATERNARY   PERIOD.  341 

excavation  of  the  valley  had  proceeded  to  a  much  less  extent. 
These  (fig.  255,  44')  are  the  so-called  "high-level  gravels" 
of  a  river,  and  there  may  be  one  or  more  terraces  of  these. 

The  important  fact  to  remember  about  these  fluviatile  de- 
posits is  this — that  here  the  ordinary  geological  rule  is  reversed. 
The  high-level  gravels  are,  of  course,  the  highest,  so  far  as 
their  actual  elevation  above  the  sea  is  concerned ;  but  geo- 
logically the  lowest,  since  they  are  obviously  much  older  than 
the  low-level  gravels,  as  these  are  than  the  recent  gravels. 
How  much  older  the  high-level  gravels  may  be  than  the  low- 
level  ones,  it  is  impossible  to  say.  They  occur  at  heights 
varying  from  10  to  100  feet  above  the  present  river-chan 
nels,  and  they  are  therefore  older  than  the  recent  gravels 
by  the  time  required  by  the  river  to  dig  out  its  own  bed  to 
this  depth.  How  long  this  period  may  be,  our  data  do  not 
enable  us  to  determine  accurately;  but  if  we  are  to  calculate 
from  the  observed  rate  of  erosion  of  the  actually  existing 
rivers,  the  period  between  the  different  valley -gravels  must 
be  a  very  long  one. 

The  lowest  or  recent  fluviatile  deposits  which  occur  beside 
the  bed  of  the  present  river,  are  referable  to  the  Recent  period, 
as  they  contain  the  remains  of  none  but  living  Mammals.  The 
two  other  sets  of  gravels  are  Post-Pliocene,  as  they  contain 
the  bones  of  extinct  Mammals,  mixed  with  land  and  fresh- 
water shells  of  existing  species.  Among  the  more  important 
extinct  Mammals  of  the  low-level  and  high-level  valley-gravels 
may  be  mentioned  the  Elephas  antiquus,  the  Mammoth  (Ele- 
phas  primigenius\  the  Woolly  Rhinoceros  (R.  tichorhinus),  the 
Hippopotamus,  the  Cave-lion,  and  the  Cave-bear.  Along 
with  these  are  found  unquestionable  traces  of  the  existence 
of  Man,  in  the  form  of  rude  flint  implements  of  undoubted 
human  workmanship. 

The  so-called  "  Cave  -  deposits,"  again,  though  exhibiting 
peculiarities  due  to  the  fact  of  their  occurrence  in  caverns  or 
fissures  in  the  rocks,  are  in  many  respects  essentially  similar 
to  the  older  valley-gravels.  Caves,  in  the  great  majority  of 
instances,  occur  in  limestone.  When  this  is  not  the  case,  it 
will  generally  be  found  that  they  occur  along  lines  of  sea-coast, 
or  along  lines  which  can  be  shown  to  have  anciently  formed 
the  coast-line.  There  are  many  caves,  however,  in  the  making 
of  which  it  can  be  shown  that  the  sea  has  had  no  hand;  and 
these  are' most  of  the  caves  of  limestone  districts.  These  owe 
their  origin  to  the  solvent  action  upon  lime  of  water  holding 
carbonic  acid  in  solution.  The  rain  which  falls  upon  a  lime- 
stone district  absorbs  a  certain  amount  of  carbonic  acid  from 


342  HISTORICAL   PALEONTOLOGY. 

the  air,  or  from  the  soil.  It  then  percolates  through  the  rock, 
generally  along  the  lines  of  jointing  so  characteristic  of  lime- 
stones, and  in  its  progress  it  dissolves  and  carries  off  a  certain 
quantity  of  carbonate  of  lime.  In  this  way,  the  natural  joints 
and  fissures  in  the  rock  are  widened,  as  can  be  seen  at  the 
present  day  in  any  or  all  limestone  districts.  By  a  continu- 
ance of  this  action  for  a  sufficient  length  of  time,  caves  may 
ultimately  be  produced.  Nothing,  also,  is  commoner  in  a 
limestone  district  than  for  the  natural  drainage  to  take  the 
line  of  some  fissure,  dissolving  the  rock  in  its  course.  In  this 
way  we  constantly  meet  in  limestone  districts  with  springs 
issuing  from  the  limestone  rock — sometimes  as  large  rivers — 
the  waters  of  which  are  charged  with  carbonate  of  lime,  ob- 
tained by  the  solution  of  the  sides  of  the  fissure  through  which 
the  waters  have  flowed.  By  these  and  similar  actions,  every 
district  in  which  limestones  are  extensively  developed  will  be 
found  to  exhibit  a  number  of  natural  caves,  rents,  or  fissures. 
The  first  element,  therefore,  in  the  production  of  cave-deposits, 
is  the  existence  of  a  period  in  which  limestone  rocks  were 
largely  dissolved,  and  caves  were  formed  in  consequence  of 
the  then  existing  drainage  taking  the  line  of  some  fissure. 

Secondly,  there  must  have  been  a  period  in  which  various 
deposits  were  accumulated  in  the  caves  thus  formed.  These 
cavern-deposits  are  of  very  various  nature,  consisting  of  mud, 
loam,  gravel,  or  breccias  of  different  kinds.  In  all  cases,  these 
materials  have  been  introduced  into  the  cave  at  some  period 
subsequent  to,  or  contemporaneous  with,  the  formation  of  the 
cave.  Sometimes  the  cave  communicates  with  the  surface  by 
a  fissure  through  which  sand,  gravel,  &c.,  may  be  washed  by 
rains  or  by  floods  from  some  neighbouring  river.  Sometimes 
the  cave  has  been  the  bed  of  an  ancient  stream,  and  the  de- 
posits have  been  formed  as  are  fluviatile  deposits  at  the  surface. 
Or,  again,  the  river  has  formerly  flowed  at  a  greater  elevation 
than  it  does  at  present,  and  the  cave  has  been  filled  with 
fluviatile  deposits  by  the  river  at  a  time  prior  to  the  excava- 
tion of  its  bed  to  the  present  depth  (fig.  256).  In  this  last 
case,  the  cave-deposits  obviously  bear  exactly  the  same  rela- 
tion in  point  of  antiquity  to  recent  deposits,  as  do  the  low- 
level  and  high-level  valley-gravels  to  recent  river-gravels.  In 
any  case,  it  is  necessary  for  the  physical  geography  of  the  dis- 
trict to  change  to  some  extent,  in  order  that  the  cave-deposits 
should  be  preserved.  If  the  materials  have  been  introduced 
by  a  fissure,  the  cave  will  probably  become  ultimately  filled 
to  the  roof,  and  the  aperture  of  admission  thus  blocked  up. 
If  a  river  has  flowed  through  the  cave,  the  surface  configura- 


THE  QUATERNARY   PERIOD. 


343 


tion  of  the  district  must  be  altered  so  far  as  to  divert  the  river 
into  a  new  channel.  And  if  the  cave  is  placed  in  the  side  of 
a  river- valley,  as  in  fig.  256,  the  river  must  have  excavated 


Fig.  256. — Diagrammatic  section  across  a  river-valley  and  cave,  a  a.  Recent  valley- 
gravels  near  the  channel  (b)  of  the  existing  river ;  c,  Cavern,  partly  filled  with  cave- 
earth  ;  d d,  High-level  gravels,  filling  fissures  in  the  limestone,  which  perhaps  communi- 
cate in  some  instances  with  the  cave,  and  form  a  channel  by  which  materials  of  various 
kinds  were  introduced  into  it ;  e  e ,  Inclined  beds  of  limestone. 

its  channel  to  such  a  depth  that  it  can  no  longer  wash  out  the 
contents  of  the  cave  even  in  high  floods. 

If  the  cave  be  entirely  filled,  the  included  deposits  generally 
get  more  or  less  completely  cemented  together  by  the  percola- 
tion through  them  of  water  holding  carbonate  of  lime  in  solu- 
tion. If  the  cave  is  only  partially  filled,  the  dropping  of  water 
from  the  roof  holding  lime  in  solution,  and  its  subsequent 
evaporation,  would  lead  to  the  formation  over  the  deposits 
below  of  a  layer  of  stalagmite,  perhaps  several  inches,  or  even 
feet,  in  thickness.  In  this  way  cave-deposits,  with  their  con- 
tained remains,  may  be  hermetically  sealed  up  and  preserved 
without  injury  for  an  altogether  indefinite  period  of  time. 

In  all  caves  in  limestone  in  which  deposits  containing  bones 
are  found,  we  have  then  evidence  of  three  principal  sets  of 
changes,  (i.)  A  period  during  which  the  cave  was  slowly 
hollowed  out  by  the  percolation  of  acidulated  water ;  (2.)  A 
period  in  which  the  cave  became  the  channel  of  an  engulfed 
river,  or  otherwise  came  to  form  part  of  the  general  drainage- 
system  of  the  district;  (3.)  A  period  in  which  the  cave  was 
inhabited  by  various  animals. 

As  a  typical  example  of  a  cave  with  fossiliferous  Post- 
Pliocene  deposits,  we  may  take  Kent's  Cavern,  near  Torquay, 
in  which  a  systematic  and  careful  examination  has  revealed  the 
following  sequence  of  accumulations  in  descending  order : — 

(a)  Large  blocks  of  limestone,  which  lie  on  the  floor  of  the 
cave,  having  fallen  from  the  roof,  and  which  are  sometimes 
cemented  together  by  stalagmite. 

(b)  A  layer  of  black  mould,  from  three  to  twelve  inches 
thick,  with  human  bones,  fragments  of  pottery,   stone   and 


344  HISTORICAL   PALEONTOLOGY. 

bronze  implements,  and  the  bones  of  animals  now  living  in 
Britain.     This,  therefore,  is  a  recent  deposit. 

(c)  A  layer  of   stalagmite,  from   sixteen  to   twenty  inches 
thick,  but  sometimes  as  much  as  five  feet,  containing  the  bones 
of  Man,  together  with  those  of  extinct  Post-Pliocene  Mammals. 

(d)  A  bed  of  red  cave-earth,  sometimes  four  feet  in  thick- 
ness, with  numerous  bones  of  extinct  Mammals  (Mammoth, 
Cave-bear,  &c.),  together  with  human  implements  of  flint  and 
horn. 

(e)  A  second  bed  of  stalagmite,  in  places  twelve  feet  in 
thickness,  with  bones  of  the  Cave  bear. 

(/)  A  red-loam  and  cave-breccia,  with  remains  of  the  Cave- 
bear  and  human  implements. 

The  most  important  Mammals  which  are  found  in  cave- 
deposits  in  Europe  generally,  are  the  Cave-bear,  the  Cave-lion, 
the  Cave-hyaena,  the  Reindeer,  the  Musk-ox,  the  Glutton,  and 
the  Lemming — of  which  the  first  three  are  probably  identical 
with  existing  forms,  and  the  remainder  are  certainly  so — to- 
gether with  the  Mammoth  and  the  Woolly  Rhinoceros,  which 
are  undoubtedly  extinct.  Along  with  these  are  found  the 
implements,  and  in  some  cases  the  bones,  of  Man  himself,  in 
such  a  manner  as  to  render  it  absolutely  certain  that  an  early 
race  of  men  was  truly  contemporaneous  in  Western  Europe 
with  the  animals  above  mentioned. 

IV.  UNCLASSIFIED  POST-PLIOCENE  DEPOSITS. — Apart  from 
any  of  the  afore-mentioned  deposits,  there  occur  other  accumu- 
lations— sometimes  superficial,  sometimes  in  caves — which  are 
found  in  regions  where  a  "  Glacial  period  "  has  not  been  fully 
demonstrated,  or  where  such  did  not  take  place ;  and  which, 
therefore,  are  not  amenable  to  the  above  classification.  The 
most  important  of  these  are  known  to  occur  in  South  America 
and  Australia ;  and  though  their  numerous  extinct  Mammalia 
place  their  reference  to  the  Post-Pliocene  period  beyond 
doubt,  their  relations  to  the  glacial  period  and  its  deposits  in 
the  northern  hemisphere  have  not  been  precisely  determined. 


CHAPTER    XXII. 
THE   POST-PLIOCENE  PERIOD— Continued. 

As  regards  the  life  of  the  Post-Pliocene  period,  we  have,  in 
the  first  place,  to  notice  the  effect  produced  throughout  the 


FAUNA   OF   THE   POST-PLIOCENE.  345 

northern  hemisphere  by  the  gradual  supervention  of  the  Glacial 
period.  Previous  to  this  the  climate  must  have  been  temper- 
ate or  warm-temperate ;  but  as  the  cold  gradually  came  on, 
two  results  were  produced  as  regards  the  living  beings  of  the 
area  thus  affected.  In  the  first  place,  all  those  Mammals 
which,  like  the  Mammoth,  the  Woolly  Rhinoceros,  the  Lion, 
the  Hyaena,  and  the  Hippopotamus,  require,  at  any  rate,  mode- 
rately warm  conditions,  would  be  forced  to  migrate  southwards 
to  regions  not  affected  by  the  new  state  of  things.  In  the 
second  place,  Mammals  previously  inhabiting  higher  latitudes, 
such  as  the  Reindeer,  the  Musk-ox,  and  the  Lemming,  would 
be  enabled  by  the  increasing  cold  to  migrate  southwards,  and 
to  invade  provinces  previously  occupied  by  the  Elephant  and 
the  Rhinoceros.  A  precisely  similar,  but  more  slowly-executed 
process,  must  have  taken  place  in  the  sea,  the  northern  Mollus- 
ca  moving  southwards  as  the  arctic  conditions  of  the  Glacial 
period  became  established,  whilst  the  forms  proper  to  temperate 
seas  receded.  As  regards  the  readily  locomotive  Mammals, 
also,  it  is  probable  that  this  process  was  carried  on  repeatedly 
in  a  partial  manner,  the  southern  and  northern  forms  alternately 
fluctuating  backwards  and  forwards  over  the  same  area,  in  ac- 
cordance with  the  fluctuations  of  temperature  which  have  been 
shown  by  Mr  James  Geikie  to  have  characterised  the  Glacial 
period  as  a  whole.  We  can  thus  readily  account  for  the  inter- 
mixture which  is  sometimes  found  of  northern  and  southern  types 
of  Mammalia  in  the  same  deposits,  or  in  deposits  apparently 
synchronous,  and  within  a  single  district.  Lastly,  at  the  final 
close  of  the  arctic  cold  of  the  Glacial  period,  and  the  re-estab- 
lishment of  temperate  conditions  over  the  northern  hemisphere, 
a  reversal  of  the  original  process  took  place — the  northern 
Mammals  retiring  within  their  ancient  limits,  and  the  southern 
forms  pressing  northwards  and  reoccupying  their  original 
domains. 

The  Invertebrate  animals  of  the  Post-Pliocene  deposits  re- 
quire no  further  mention — all  the  known  forms,  except  a  few 
of  the  shells  in  the  lowest  beds  of  the  formation,  being  iden- 
tical with  species  now  in  existence  upon  the  globe.  The  only 
point  of  importance  in  this  connection  has  been  previously 
noticed — namely,  that  in  the  true  Glacial  deposits  themselves 
a  considerable  number  of  the  shells  belong  to  northern  or 
Arctic  types. 

As  regards  the  Vertebrate  animals  of  the  period,  no  extinct 
forms  of  Fishes,  Amphibians,  or  Reptiles  are  known  to  occur, 
but  we  meet  with  both  extinct  Birds  and  extinct  Mammals. 
The  remains  of  the  former  are  of  great  interest,  as  indicating 


346  HISTORICAL   PAL/EONTOLOGY. 

the  existence  during  Post -Pliocene  times,  at  widely  remote 
points  of  the  southern  hemisphere,  of  various  wingless,  and  for 
the  most  part  gigantic,  Birds.  All  the  great  wingless  Birds  of 
the  order  Cursores  which  are  known  as  existing  at  the  pres- 
ent day  upon  the  globe,  are  restricted  to  regions  which  are 
either  wholly  or  in  great  part  south  of  the  equator.  Thus  the 
true  Ostriches  are  African ;  the  Rheas  are  South  American  ; 
the  Emeus  are  Australian  ;  the  Cassowaries  are  confined  to 
Northern  Australia,  Papua,  and  the  Indian  Archipelago ;  the 
species  of  Apteryx  are  natives  of  New  Zealand ;  and  the 
Dodo  and  Solitaire  (wingless,  though  probably  not  true  Cur- 
sores),  both  of  which  have  been  exterminated  within  histori- 
cal times,  were  inhabitants  of  the  islands  of  Mauritius  and 
Rodriguez,  in  the  Indian  Ocean.  In  view  of  these  facts,  it 
is  noteworthy  that,  so  far  as  known,  all  the  Cursorial  Birds 
of  the  Post-Pliocene  period  should  have  been  confined  to  the 
same  hemisphere  as  that  inhabited  by  the  living  representatives 
of  the  order.  It  is  still  further  interesting  to  notice  that  the 
extinct  forms  in  question  are  only  found  in  geographical  prov- 
inces which  are  now,  or  have  been  within  historical  times,  inhab- 
ited by  similar  types.  The  greater  number  of  the  remains  of 
these  have  been  discovered  in  New  Zealand,  where  there  now 
live  several  species  of  the  curious  wingless  genus  Apteryx  ;  and 
they  have  been  referred  by  Professor  Owen  to  several  generic 
groups,  of  which  Dinornis  is  the  most  important  (fig.  257). 
Fourteen  species  of  Dinornis  have  been  described  by  the  dis- 
tinguished palaeontologist  just  mentioned,  all  of  them  being 
large  wingless  birds  of  the  type  of  the  existing  Ostrich,  having 
enormously  powerful  hind-limbs  adapted  for  running,  but  with 
the  wings  wholly  rudimentary,  and  the  breast-bone  devoid  of 
the  keel  or  ridge  which  characterises  this  bone  in  all  birds 
which  fly.  The  largest  species  is  the  Dinornis  giganteus,  one 
of  the  most  gigantic  of  living  or  fossil  birds,  the  shank  (tibia) 
measuring  a  yard  in  length,  and  the  total  height  being  at  least 
ten  feet.  Another  species,  the  Dinornis  elephantopus  (fig.  257), 
though  not  standing  more  than  about  six  feet  in  height,  was 
of  an  even  more  ponderous  construction — "the  framework 
of  the  skeleton  being  the  most  massive  of  any  in  the  whole 
class  of  Birds,"  whilst  "  the  toe-bones  almost  rival  those  of  the 
Elephant"  (Owen).  The  feet  in  Dinornis  were  furnished  with 
three  toes,  and  are  of  interest  as  presenting  us  with  an  un- 
doubted Bird  big  enough  to  produce  the  largest  of  the  foot- 
prints of  the  Triassic  Sandstones  of  Connecticut.  New  Zea- 
land has  now  been  so  far  explored,  that  it  seems  questionable 
if  it  can  regain  in  its  recesses  any  living  example  of  Dinornis  ; 


FAUNA   OF   THE   POST-PLIOCENE. 


347 


but  it  is  certain  that  species  of  this  genus  were  alive  during  the 
human  period,  and  survived  up  to  quite  a  recent  date.  Not 
only  are  the  bones  very  numerous  in  certain  localities,  but 


Fig.  257. — Skeleton  \ADhtomiselepkanioptts,  greatly  reduced.     Post-Pliocene, 
New  Zealand.     (After  Owen.) 

they  are  found  in  the  most  recent  and  superficial  deposits,  and 
they  still  contain  a  considerable  proportion  of  animal  matter; 
whilst  in  some  instances  bones  have  been  found  with  the 
feathers  attached,  or  with  the  horny  skin  of  the  legs  still  ad- 
hering to  them.  Charred  bones  have  been  found  in  connec- 
tion with  native  "ovens;"  and  the  traditions  of  the  Maories 
contain  circumstantial  accounts  of  gigantic  wingless  Birds,  the 
"  Moas,"  which  were  hunted  both  for  their  flesh  and  their 
plumage.  Upon  the  whole,  therefore,  there  can  be  no  doubt 


34^  HISTORICAL   PALAEONTOLOGY. 

but  that  the  Moas  of  New  Zealand  have  been  exterminated  at 
quite  a  recent  period — perhaps  within  the  last  century — by  the 
unrelenting  pursuit  of  Man, — a  pursuit  which  their  wingless 
condition  rendered  them  unable  to  evade. 

In  Madagascar,  bones  have  been  discovered  of  another  huge 
wingless  Bird,  which  must  have  been  as  large  as,  or  larger 
than,  the  Dinornis  giganteus,  and  which  has  been  described 
under  the  name  of  jiLpiornis  maximus.  With  the  bones  have 
been  found  eggs  measuring  from  thirteen  to  fourteen  inches  in 
diameter,  and  computed  to  have  the  capacity  of  three  Ostrich 
eggs.  At  least  two  other  smaller  species  Qi^Epiornis  have  been 
described  by  Grandidier  and  Milne-Edwards  as  occurring  in 
Madagascar;  and  they  consider  the  genus  to  be  so  closely  allied 
to  the  Dinornis  of  New  Zealand,  as  to  prove  that  these  regions, 
now  so  remote,  were  at  one  time  united  by  land.  Unlike  New 
Zealand,  where  there  is  the  Apteryx,  Madagascar  is  not  known 
to  possess  any  living  wingless  Birds  ;  but  in  the  neighbouring 
island  of  Mauritius  the  wingless  Dodo  (Didus  ineptus)  has  been 
exterminated  less  than  three  hundred  years  ago ;  and  the  little 
island  of  Rodriguez,  in  the  same  geographical  province,  has  in 
a  similar  period  lost  the  equally  wingless  Solitaire  (Pezophaps), 
both  of  these,  however,  being  generally  referred  to  the  Rasores. 
The  Mammals  of  the  Post-Pliocene  period  are  so  numerous, 
that  in  spite  of  the  many  points  of  interest  which  they  present, 
only  a  few  of  the  more  important  forms  can  be  noticed  here, 
and  that  but  briefly.  The  first  order  that  claims  our  attention 
is  that  of  the  Marsupials,  the  headquarters  of  which  at  the 
present  day  is  the  Australian  province.  In  Oolitic  times 
Europe  possessed  its  small  Marsupials,  and  similar  forms 
existed  in  the  same  area  in  the  Eocene  and  Miocene  periods ; 
but  if  size  be  any  criterion,  the  culminating  point  in  the  history 
of  the  order  was  attained  during  the  Post-Pliocene  period  in 

Australia.  From  deposits  of 
this  age  there  has  been  disen- 
tombed a  whole  series  of  re- 
mains of  extinct,  and  for  the 
most  part  gigantic,  examples 
of  this  group  of  Quadrupeds. 
Not  to  speak  of  Wombats  and 
Phalangers,  two  forms  stand 
out  prominently  as  represen- 
tatives  of  the  Post-Pliocene 
animals  of  Australia.  One  of 
these  is  Diprotodon  (fig.  258),  representing,  with  many  differ- 
ences, the  well-known  modern  group  of  the  Kangaroos.  In 


FAUNA   OF   THE   POST-PLIOCENE.  349 

its  teeth,  Diprotodon  shows  itself  to  be  closely  allied  to  the 
living,  grass-eating  Kangaroos ;  but  the  hind-limbs  were  not 
so  disproportionately  long.  In  size,  also,  Diprotodon  must 
have  many  times  exceeded  the  dimensions  of  the  largest  of 
its  living  successors,  since  the  skull  measures  no  less  than 
three  feet  in  length.  The  other  form  in  question  is  Tkylacolco 
(fig.  259),  which  is  believed  by  Professor  Owen  to  belong  to 
the  same  group  as  the  existing  "  Native  Devil "  (Dasyurus)  of 
Van  Diemen's  Land,  and  therefore  to  have  been  flesh-eating 
and  rapacious  in  its  habits,  though  this  view  is  not  accepted 
by  others.  The  principal  feature  in  the  skull  of  Thylacolco  is 


Fig.  259.  —Skull  of  Thylctcflleo.     Post-PIiocere.  Australia.     Greatly  reduced. 
(After  Flower.) 

the  presence,  on  each  side  of  each  jaw,  of  a  single  huge  tooth, 
which  is  greatly  compressed,  and  has  a  cutting  edge.  This 
tooth  is  regarded  by  Owen  as  corresponding  to  the  great  cut- 
ting tooth  of  the  jaw  of  the  typical  Carnivores,  but  Professor 
Flower  considers  that  Thylacoleo  is  rather  related  to  the  Kan- 
garoo-rats. The  size  of  the  crown  of  the  tooth  in  question  is 
not  less  than  two  inches  and  a  quarter  :  and  whether  carnivo- 
rous or  not,  it  indicates  an  animal  of  a  size  exceeding  that  of 
the  largest  of  existing  Lions. 

The  order  of  the  Edentates,  comprising  the  existing  Sloths, 
Ant-eaters,  and  Armadillos,  and  entirely  restricted  at  the  present 
day  to  South  America.  Southern  Asia,  and  Africa,  is  one  alike 


350  HISTORICAL   PALAEONTOLOGY. 

singular  for  the  limited  geographical  range  of  its  members, 
their  curious  habits  of  life,  and  the  well-marked  peculiarities 
of  their  anatomical  structure.  South  America  is  the  metropo- 
lis of  the  existing  forms  ;  and  it  is  an  interesting  fact  that  there 
flourished  within  Post-Pliocene  times  in  this  continent,  and  to 
some  extent  in  North  America  also,  a  marvellous  group  of  ex- 
tinct Edentates,  representing  the  living  Sloths  and  Armadillos, 
but  of  gigantic  size.  The  most  celebrated  of  these  is  the  huge 
Megatherium  Cuvieri  (fig.  260)  of  the  South  American  Pampas. 


Fig.  260. — Megatherium  Cuv'eri.     Post-Pliocene,  South  America. 

The  Megathere  was  a  colossal  Sloth-like  animal  which  attained 
a  length  of  from  twelve  to  eighteen  feet,  with  bones  more  mas- 
sive than  those  of  the  Elephant.  Thus  the  thigh-bone  is 
nearly  thrice  the  thickness  of  the  same  bone  in  the  largest 
of  existing  Elephants,  its  circumference  at  its  narrowest  point 
nearly  equalling  its  total  length  ;  the  massive  bones  of  the 
shank  (tibia  and  fibula)  are  amalgamated  at  their  extremities  ; 
the  heel-bone  (calcaneum)  is  nearly  half  a  yard  in  length  ;  the 
haunch-bones  (ilia)  are  from  four  to  five  feet  across  at  their 
crests ;  and  the  bodies  of  the  vertebrae  at  the  root  of  the  tail 
are  from  five  to  seven  inches  in  diameter,  from  which  it  has 
been  computed  that  the  circumference  of  the  tail  at  this  part 
might  have  been  from  five  to  six  feet.  The  length  of  the  fore- 
foot is  about  a  yard,  and  the  toes  are  armed  with  powerful 
curved  claws.  It  is  known  now  that  the  Megathere,  in  spite 
of  its  enormous  weight  and  ponderous  construction,  walked, 
like  the  existing  Ant-eaters  and  Sloths,  upon  the  outside  edge 
of  the  fore-feet,  with  the  claws  more  or  less  bent  inwards 


FAUNA   OF   THE    POST-PLIOCENE.  351 

towards  the  palm  of  the  hand.  As  in  the  great  majority  of 
the  Edentate  order,  incisor  and  canine  teeth  are  entirely 
wanting,  the  front  of  the  jaws  being  toothless.  The  jaws, 
however,  are  furnished  with  five  upper  and  four  lower  molar 
teeth  on  each  side.  These  grinding  teeth  are  from  seven  to 
eight  inches  in  length,  in  the  form  of  four-sided  prisms,  the 
crowns  of  which  are  provided  with  well-marked  transverse 
ridges;  and  they  continue  to  grow  during  the  whole  life  of 
the  animal.  There  are  indications  that  the  snout  was  pro- 
longed, and  more  or  less  flexible;  and  the  tongue  was  proba- 
bly prehensile.  From  the  characters  of  the  molar  teeth  it 
is  certain  that  the  Megathere  was  purely  herbivorous  in  its 
habits ;  and  from  the  enormous  size  and  weight  of  the  body, 
it  is  equally  certain  that  it  could  not  have  imitated  its  modern 
allies,  the  Sloths,  in  the  feat  of  climbing,  back  downwards, 
amongst  the  trees.  It  is  clear,  therefore,  that  the  Megathere 
sought  its  sustenance  upon  the  ground ;  and  it  was  originally 
supposed  to  have  lived  upon  roots.  By  a  masterly  piece  of 
deductive  reasoning,  however,  Professor  Owen  showed  that 
this  great  "  Ground-Sloth "  must  have  truly  lived  upon  the 
foliage  of  trees,  like  the  existing  Sloths — but  with  this  differ- 
ence, that  instead  of  climbing  amongst  the  branches,  it  actually 
uprooted  the  tree  bodily.  In  this  tour  de  force,  the  animal 
sat  upon  its  huge  haunches  and  mighty  tail,  as  on  a  tripod, 
and  then  grasping  the  trunk  with  its  powerful  arms,  either 
wrenched  it  up  by  the  roots  or  broke  it  short  off  above  the 
ground.  Marvellous  as  this  may  seem,  it  can  be  shown  that 
every  detail  in  the  skeleton  of  the  Megathere  accords  with  the 
supposition  that  it  obtained  its  food  in  this  way.  Similar 
habits  were  followed  by  the  allied  Mylodon  (fig.  261),  another 
of  the  great  "  Ground-Sloths,"  which  inhabited  South  America 
during  the  Post-Pliocene  period.  In  most  respects,  the  Mylo- 
don is  very  like  the  Megathere ;  but  the  crowns  of  the  molar 
teeth  are  flat  instead  of  being  ridged.  The  nearly-related 
genus  Megalonyx,  unlike  the  Megathere,  but  like  the  Mylodon, 
extended  its  range  northwards  as  far  as  the  United  States. 

Just  as  the  Sloths  of  the  present  day  were  formerly  repre- 
sented in  the  same  geographical  area  by  the  gigantic  Megathe- 
roids,  so  the  little  banded  and  cuirassed  Armadillos  of  South 
America  were  formerly  represented  by  gigantic  species,  con- 
stituting the  genus  Glyptodon.  The  Glyptodons  (fig.  262) 
differed  from  the  living  Armadillos  in  having  no  bands  in 
their  armour,  so  that  they  must  have  been  unable  to  roll 
themselves  up.  It  is  rare  at  the  present  day  to  meet  with  any 
Armadillo  over  two  or  three  feet  in  length;  but  the  length  of 


35 2  HISTORICAL    PALEONTOLOGY. 

the  Glyptodon  davipes,  from  the  tip  of  the  snout  to  the  end  of 
the  tail,  was  more  than  nine  feet. 

There  are  no  canine  or  incisor  teeth  in  the  Glyptodon^  but 


Fig.  261.  —  Skeleton  of  Mylodon  robnstns.     Post- Pliocene,  South  America. 

there  are  eight  molars  on  each  side  of  each  jaw,  and  the  crowns 
of  these  are  fluted  and  almost  trilobed.     The  head  is  covered 


Fig.  262.— Skeleton  of  Glyptodon  clavifes.      Post-Pliocene,  South  America. 

by  a  helmet  of  bony  plates,  and  the  trunk  was  defended  by  an 
armour  of  almost  hexagonal  bony  pieces  united  by  sutures,  and 


FAUNA   OF   THE    POST-PLIOCENE.  353 

exhibiting  special  patterns  of  sculpturing  in  each  species.  The 
tail  was  also  defended  by  a  similar  armour,  and  the  vertebrae 
were  mostly  fused  together  so  as  to  form  a  cylindrical  bony 
rod.  In  addition  to  the  above-mentioned  forms,  a  number 
of  other  Edentate  animals  have  been  discovered  by  the  re- 
searches of  M.  Lund  in  the  Post-Pliocene  deposits  of  the 
Brazilian  bone-caves.  Amongst  these  are  true  Ant-eaters, 
Armadillos,  and  Sloths,  many  of  them  of  gigantic  size,  and  all 
specifically  or  generically  distinct  from  existing  forms. 

Passing  over  the  aquatic  orders  of  the  Sirenians  and  Ce- 
taceans, we  come  next  to  the  great  group  of  the  Hoofed  Quad- 
rupeds, the  remains  of  which  are  very  abundant  in  Post- 
Pliocene  deposits  both  in  Europe  and  North  America. 
Amongst  the  Odd -toed  Ungulates  the  mo^t  important  are 
the  Rhinoceroses,  of  which  three  species  are  known  to  have 
existed  in  Europe  during  the  Post-Pliocene  period.  Two 
of  these  are  the  well-known  Pliocene  forms,  the  Rhinoceros 
Etruscus  and  the  R.  megarhinus,  still  surviving  in  diminished 
numbers ;  but  the  most  famous  is  the  Rhinoceros  tichorhinus 
(fig.  263),  or  so-called  "  Woolly  -Rhinoceros."  This  species 


Fig.  263. — Skull  of  the  Tichorhine  Rhinoceros,  the  horns  being  wanting.     One-tenth 
of  the  natural  size.     Post-Pliocene  deposits  of  Europe  and  Asia. 

is  known  not  only  by  innumerable  bones,  but  also  by  a  car- 
cass, at  the  time  of  its  discovery  complete,  which  was  found 
embedded  in  the  frozen  soil  of  Siberia  towards  the  close  of 
last  century,  and  which  was  partly  saved  from  destruction  by 
the  exertions  of  the  naturalist  Pallas.  From  this,  we  know 
that  the  Tichorhine  Rhinoceros,  like  its  associate  the  Mam- 
moth, was  provided  with  a  coating  of  hair,  and  therefore  was 
enabled  to  endure  a  more  severe  climate  than  any  existing 


354  HISTORICAL   PAL/EONTOLOGY. 

species.  The  skin  was  not  thrown  into  the  folds  which  char- 
acterise most  of  the  existing  forms ;  and  the  technical  name 
of  the  species  refers  to  the  fact  that  the  nostrils  were  com- 
pletely separated  by  a  bony  partition.  The  head  carried  two 
horns,  placed  one  behind  the  other,  the  front  one  being  un- 
usually large.  As  regards  its  geographical  range,  the  Woolly 
Rhinoceros  is  found  in  Europe  in  vast  numbers  north  of  the 
Alps  and  Pyrenees,  and  it  also  abounded  in  Siberia ;  so  that 
it  would  appear  to  be  a  distinctly  northern  form,  and  to  have 
been  adapted  for  a  temperate  climate.  It  is  not  known  to 
occur  in  Pliocene  deposits,  but  it  makes  its  first  appearance 
in  the  Pre-Glacial  deposits,  surviving  the  Glacial  period,  and 
being  found  in  abundance  in  Post-Glacial  accumulations.  It 
was  undoubtedly  a  contemporary  of  the  earlier  races  of  men 
in  Western  Europe ;  and  it  may  perhaps  be  regarded  as  being 
i  the  actual  substantial  kernel  of  some  of  the  "  Dragons  "  of 
fable. 

The  only  other  Odd-toed  Ungulate  which  needs  notice  is 
the  so-called  Equus  fossilis  of  the  Post-Pliocene  of  Europe. 
This  made  its  appearance  before  the  Glacial  period,  and  ap- 
pears to  be  in  reality  identical  with  the  existing  Horse  (Equus 
caballus)  True  Horses  also  occur  in  the  Post-Pliocene  of 
North  America ;  but,  from  some  cause  or  another,  they  must 
have  been  exterminated  before  historic  times. 

Amongst  the  Even-toed  Ungulates,  the  great  Hippopotamus 
major  of  the  Pliocene  still  continued  to  exist  in  Post-Pliocene 
times  in  Western  Europe ;  and  the  existing  Wild  Boar  (Sus 
scrofa\  the  parent  of  our  domestic  breeds  of  Pigs,  appeared 
i  for  the  first  time.  The  Old  World  possessed  extinct  repre- 
'  sentatives  of  its  existing  Camels,  and  lost  types  of  the  living 
Llamas  inhabited  South  America.  Amongst  the  Deer,  the 
Post- Pliocene  accumulations  have  yielded  the  remains  of 
various  living  species,  such  as  the  Red  Deer  (Cervus  elaphus\ 
the  Reindeer  (Cervus  tarandus),  the  Moose  or  Elk  (Alces 
malchis\  and  the  Roebuck  (Cervus  capreolus),  together  with 
a  number  of  extinct  forms.  Among  the  latter,  the  great 
"Irish  Elk"  (Ceiiws  megaceros)  is  justly  celebrated  both  for 
its  size  and  for  the  number  and  excellent  preservation  of  its 
discovered  remains.  This  extinct  species  (fig.  264)  has  been 
found  principally  in  peat -mosses  and  Post- Pliocene  lake- 
deposits,  and  is  remarkable  for  the  enormous  size  of  the 
spreading  antlers,  which  are  widened  out  towards  their  ex- 
tremities, and  attain  an  expanse  of  over  ten  feet  from  tip  to 
tip.  It  is  not  a  genuine  Elk,  but  is  intermediate  between 
the  Reindeer  and  the  Fallow-deer.  Among  the  existing  Deer 


FAUNA   OF    THE   POST-PLIOCENE. 


355 


of  the  Post-Pliocene,  the  most   noticeable   is   the  Reindeer, 
an  essentially  northern  type,  existing  at  the  present  day  in 


Fig.  264. — Skeleton  of  the  "  Irish  Elk"  (CervTismegaceros). 
Pos>Pliccene,  Britain. 

Northern  Europe,  and  also  (under  the  name  of  the  "  Caribou") 
in  North  America.  When  the  cold  of  the  Glacial  period  be- 
came established,  this  boreal  species  was  enabled  to  invade 
Central  and  Western  Europe  in  great  herds,  and  its  remains 
are  found  abundantly  in  cave-earths  and  other  Post-Pliocene 
deposits  as  far  south  as  the  Pyrenees. 

In  addition  to  the  above,  the  Post -Pliocene  deposits  of 
Europe  and  North  America  have  yielded  the  remains  of  vari- 
ous Sheep  and  Oxen.  One  of  the  most  interesting  of  the 


356  HISTORICAL  PALEONTOLOGY. 

fatter  is  the  *  Unis"  or  Wild  Bull  (Bos  primigenius,  fig.  265). 
which,  though  much  larger  than  any  of  the  existing  forms,  is 


'  ~  --'-• 


befitted  to  be  specifically  indistinguishable  from  the  domes- 
tic Ox  (Bos  taunts),  and  to  be  possibly  the  ancestor  of  some 
of  the  larger  European  varieties  of  oxen.  In  the  earlier  part 
of  its  existence  the  Urns  ranged  over  Europe  and  Britain  in 
company  with  the  Woolly  Rhinoceros  and  the  Mammoth ;  but 
it  long  survived  these,  and  does  not  appear  to  have  been 
finally  exterminated  till  about  the  twelfth  century.  Another 
remarkable  member  of  the  Post-Pliocene  Cattle,  also  to  be- 
gin with  an  associate  of  the  Mammoth  and  Rhinoceros,  is 
the  European  Bison  or  "Aurochs'*  (Bison  priscus).  This 
"maned"  ox  formerly  abounded  in  Europe  in  Post-Glacial 
tones,  and  was  not  rare  even  in  the  later  periods  of  the 
Roman  empire,  though  jmch  diminished  in  numbers,  and 
driven  back  into  the  wilder  and  more  inaccessible  parts  of  the 
country.  At  present  this  fine  species  has  been  so  nearly 
fii^iiiimafiffd  that  it  no  longer  exists  in  Europe  save  in 
TirhnrmiaT  where  its  preservation  has  been  secured  by  rigid 
protective  laws.  Lastly,  the  Post -Pliocene  deposits  have 
yielded  the  remains  of  the  singular  living  animal  which  is 
known  as  the  Musk-ox  or  Musk-sheep  (Ovibos  moschatus). 
At  the  present  day,  the  Musk-ox  is  an  inhabitant  of  the 
**  barren  grounds'7  of  Arctic  America,  and  it  is  remarkable  for 
the  great  length  of  its  hair.  It  is,  like  the  Reindeer,  a  dis- 


FAUNA   OF   THE   POST-PLIOCEXE,  357 

tinctively  northern  animal ;  but  it  enjoyed  during  the  Glacial 
period  a  much  wider  range  than  it  has  at  the  present  day,  the 
conditions  suitable  for  its  existence  being  then  extended  over 
a  considerable  portion  of  the  northern  hemisphere.  Thus 
remains  of  the  Musk-Ox  are  found  in  greater  or  less  abun- 
dance in  Post-Pliocene  deposits  over  a  great  part  of  Europe, 
extending  even  to  the  south  of  France;  and  closely -related 
forms  are  found  in  similar  deposits  in  the  United  States. 

Coming  to  the  Proboscideans,  we  find  that  the  Mastodons 
seem  to  have  disappeared  in  Europe  at  the  close  of  the 
Pliocene  period,  or  at  the  very  commencement  of  the  Post- 
Pliocene.  In  the  Xew  World,  on  the  other  hand,  a  species  of 
Mastodon  (J/.  Ameruanus  or  M.  Ohiotiais)  is  found  abun- 
dantly in  deposits  of  Post  -  Pliocene  age,  from  Canada  to 
Texas.  Very  perfect  skeletons  of  this  species  have  been 
exhumed  from  morasses  and  swamps,  and  large  individuals 
attained  a  length  (exclusive  of  the  tusks)  of  seventeen  feet  and 
a  height  of  eleven  feet,  the  tusks  being  twelve  feet  in  length. 
Remains  of  Elephants  are  also  abundant  in  the  Post-Pliocene 
deposits  of  both  the  Old  and  the  Xew  World.  Amongst  these, 
we  find  in  Europe  the  two  familiar  Pliocene  species  E.  meri- 
dionalis  and  E.  antiquus  still  surviving,  but  in  diminished 
numbers.  With  these  are  found  in  vast  abundance  the  re- 
mains of  the  characteristic  Elephant  of  the  Post-Pliocene,  the 
well-known  "  Mammoth  "  (Eiephas  primigenius\  which  is  ac- 
companied in  North  America  by  the  nearly-allied,  but  more 
southern  species,  the  Eiephas  Ameritanus.  The  Mammoth  (fig. 
266)  is  considerably  larger  than  the  largest  of  the  living  Ele- 
phants, the  skeleton  being  over  sixteen  feet  in  length,  exclusive 
of  the  tusks,  and  over  nine  feet  in  height  The  tusks  are  bent 
almost  into  a  circle,  and  are  sometimes  twelve  feet  in  length, 
measured  along  their  curvature.  In  the  frozen  soil  of  Siberia 
several  carcasses  of  the  Mammoth  have  been  discovered  with 
the  flesh  and  skin  still  attached  to  the  bones,  the  most  cele- 
brated of  these  being  a  Mammoth  which  was  discovered  at  the 
beginning  of  this  century  at  the  mouth  of  the  Lena,  on  the  borders 
of  the  Frozen  Sea,  and  the  skeleton  of  which  is  now  preserved 
at  St  Petersburg  (fig.  266).  From  the  occurrence  of  the  remains 
of  the  Mammoth  in  vast  numbers  in  Siberia,  it  might  have  been 
safely  inferred  that  this  ancient  Elephant  was  able  to  endure  a  far 
more  rigorous  climate  than  its  existing  congeners.  This  infer- 
ence has,  however,  been  rendered  a  certainty  by  the  specimens 
just  referred  to,  which  show  that  the  Mammoth  was  protected 
against  the  cold  by  a  thick  coat  of  reddish-brown  wool,  some 
nine  or  ten  inches  long,  interspersed  with  strong,  coarse  black 


358 


HISTORICAL   PALEONTOLOGY. 


hair  more  than  a  foot  in  length.  The  teeth  of  the  Mammoth 
(fig.  267)  are  of  the  type  of  those  of  the  existing  Indian  Ele- 
phant, and  are  found  in  immense  numbers  in  certain  localities. 


The  Mammoth  was  essentially  northern  in  its  distribution, 
never  passing  south  of  a  line  drawn  through  the  Pyrenees,  the 
Alps,  the  northern  shores  of  the  Caspian,  Lake  Baikal,  Kara- 


FAUNA   OF   THE   POST-PLIOCENE.  359 

schatka,  and  the  Stanovi  Mountains  (Dawkins).     It  occurs  in 
the  Pre-Glacial  forest-bed  of  Cromer  in  Norfolk,  survived  the 


Fig.  267. — Molar  tooth  of  the  Mammoth  (Rlephas  primigenhts),  upper  jaw,  right  side, 
one-third  of  the  natural  size,     a,  Grinding  surface  ;  b,  Side  view.     Post- Pliocene. 

Glacial  period,  and  is  found  abundantly  in  Post-Glacial  de- 
posits in  France,  Germany,  Britain,  Russia  in  Europe,  Asia, 
and  North  America,  being  often  associated  with  the  Reindeer, 
Lemming,  and  Musk-ox.  That  it  survived  into  the  earlier 
portion  of  the  human  period  is  unquestionable,  its  remains 
having  been  found  in  a  great  number  of  instances  associated 
with  implements  of  human  manufacture  ;  whilst  in  one  instance 
a  recognisable  portrait  of  it  has  been  discovered,  carved  on 
bone. 

Amongst  other  Elephants  which  occur  in  Post-Pliocene  de- 
posits may  be  mentioned,  as  of  special  interest,  the  pigmy 
Elephants  of  Malta.  One  of  these — the  Elephas  Melitensis,  or 
so-called  "Donkey-Elephant" — was  not  more  than  four  and 
a  half  feet  in  height.  The  other — the  Elephas  Falconeri,  of 
Busk — was  still  smaller,  its  average  height  at  the  withers  not 
exceeding  two  and  a  half  to  three  feet. 

Whilst  herbivorous  animals  abounded  during  the  Post- 
Pliocene,  we  have  ample  evidence  of  the  coexistence  with 
them  of  a  number  of  Carnivorous  forms,  both  in  the  New  and 
the  Old  World.  The  Bears  are  represented  in  Europe  by  at 
least  three  species,  two  of  which — namely,  the  great  Grizzly 
Bear  (Ursus  ferox)  and  the  smaller  Brown  Bear  (Ursus  arctos) 
— are  in  existence  at  the  present  day.  The  third  speciesis  the 


HISTORICAL   PALAEONTOLOGY. 


celebrated  Cave-bear  (Ursns  spelceus,  fig.  268),  which  is  now 
extinct.     The  Cave-bear  exceeded  in  its  dimensions  the  largest 


Fig.  268.  — Skull  of  Ursns  sf>el(rns.     Post-Pliocene,  Europe.     One-sixth 
of  the  natural  size. 

of  modern  Bears;  and  its  remains,  as  its  name  implies,  have 
been  found  mainly  in  cavern-deposits.  Enormous  numbers  of 
this  large  and  ferocious  species  must  have  lived  in  Europe  in 
Post-Glacial  times ;  and  that  they  survived  into  the  human 
period,  is  clearly  shown  by  the  common  association  of  their 
bones  with  the  implements  of  man.  They  are  occasionally 
accompanied  by  the  remains  of  a  Glutton  (the  Gulo  spel&us], 
which  does  not  appear  to  be  really  separable  from  the  existing 
Wolverine  or  Glutton  of  northern  regions  (the  Gulo  litscus}. 
In  addition,  we  meet  with  the  bones  of  the  Wolf,  Fox,  Weasel, 
Otter,  Badger,  Wild  Cat,  Panther,  Hyaena,  and  Lion,  &c., 
together  with  the  extinct  Machairodus  or  "  Sabre-toothed 
Tiger."  The  only  two  of  these  that  deserve  further  mention 
are  the  Hyaena  and  the  Lion.  The  Cave-hyaena  (Hycena 
spel&a,  fig.  269)  is  regarded  by  high  authorities  as  nothing 
more  than  a  variety  of  the  living  Spotted  Hyaena  (If.  crocuta] 
of  South  Africa.  This  well-known  species  inhabited  Britain 
and  a  considerable  portion  of  Europe  during  a  large  part  of 
the  Post-Pliocene  period ;  and  its  remains  often  occur  in  great 
abundance.  Indeed,  some  caves,  such  as  the  Kirkdale  Cavern 
in  Yorkshire,  were  dens  inhabited  during  long  periods  by  these 
animals,  and  thus  contain  the  remains  of  numerous  individuals 
and  of  successive  generations  of  Hysenas,  together  with  in- 
numerable gnawed  and  bitten  bones  of  their  prey.  That  the 
Cave-hyaena  was  a  contemporary  with  Man  in  Western  Europe 
during  Post-Glacial  times  is  shown  beyond  a  doubt  by  the 
common  association  of  its  bones  with  human  implements. 


FAUNA   OF    THE    POST-PLIOCENE. 


361 


Lastly,  the  so-called  Cave-lion  (Felis  spelcea),  long  supposed 
to  be  a  distinct  species,  has  been  shown  to  be  nothing  more 


Fig.  269.  — Skull  of  HyfPtia  spe'tea,  one-fourth  of  the  natural  size. 
Post- Pliocene,  Kurope. 

than  a  large  variety  of  the  existing  Lion  (Felis  lee}.  This 
animal  inhabited  Britain  and  Western  Europe  in  times  pos- 
terior to  the  Glacial  period,  and  was  a  contemporary  of  the 
Cave-hyaena,  Cave-bear,  Woolly  Rhinoceros,  and  Mammoth. 
The  Cave-lion  also  unquestionably  survived  into  the  earlier 
portion  of  the  human  period  in  Europe. 

The  Post-Pliocene  deposits  of  Europe  have  further  yielded 
the  remains  of  numerous  Rodents — such  as  the  Beaver,  the 
Northern  Lemming,  Marmots,  Mice,  Voles,  Rabbits,  &c. — to- 
gether with  the  gigantic  extinct  Beaver  known  as  the  Trogon- 
1  her  him  Cuvieri  (fig.  270).  The  great  Castoroides  Ohioensis  of 
the  Post-Pliocene  "of  North 
America  is  also  a  great  ex- 
tinct Beaver,  which  reached 
a  length  of  about  five  feet. 
Lastly,  the  Brazilian  bone- 
caves  have  yielded  the  re- 
mains of  numerous  Rodents 
of  types  now  characteristic 
of  South  America,  such  as 

f^ninpn  nicr<5   Pnnvharn<;    trpp  Fig-   27°- — Lower  jaw  of   Trogont'ierhnn 

Liuinea-pigs,  uapyoaras,  tree-     r^,?r/  7one.fourth  0£the  naturalize.   p<:st- 
mhabiting   Porcupines,   and     Pliocene,  L'main. 
Coy  pus. 

The  deposits  just  alluded  to  have  further  yielded  the 
remains  of  various  Monkeys,  such  as  Howling  Monkeys, 
Squirrel  Monkeys,  and  Marmosets,  all  of  which  belong  to  the 
group  of  Quadrumana  which  is  now  exclusively  confined  to 


362  HISTORICAL   PAL/EONTOLOGY. 

the  South  American    continent  —  namely,  the  "  Platyrhine  " 
Monkeys. 

We  still  have  very  briefly  to  consider  the  occurrence  of 
Man  in  Post-Pliocene  deposits ;  but  before  doing  so,  it  will  be 
well  to  draw  attention  to  the  evidence  afforded  by  the  Post- 
Pliocene  Mammals  as  to  the  climate  of  Western  Europe  at 
this  period.  The  chief  point  which  we  have  to  notice  is,  that 
a  considerable  revolution  of  opinion  has  taken  place  on  this 
point.  It  was  originally  believed  that  the  presence  of  such 
animals  as  Elephants,  Lions,  the  Rhinoceros,  and  the  Hippo- 
potamus afforded  an  irrefragable  proof  that  the  climate  of 
Europe  must  have  been  a  warm  one,  at  any  rate  during  Post- 
Glacial  times.  The  existence,  also,  of  numbers  of  Mammoths 
in  Siberia,  was  further  supposed  to  indicate  that  this  high  tem- 
perature extended  itself  very  far  north.  Upon  the  whole,  how- 
ever, the  evidence  is  against  this  view.  Not  only  is  there  great 
difficulty  in  supposing  that  the  Arctic  conditions  of  the  Glacial 
period  were  immediately  followed  by  anything  warmer  than  a 
cold-temperate  climate  ;  but  there  is  nothing  in  the  nature  of 
the  Mammals  themselves  which  would  absolutely  forbid  their 
living  in  a  temperate  climate.  The  Hippopotamus  major,  though 
probably  clad  in  hair,  offers  some  difficulty — since,  as  pointed 
out  by  Professor  Busk,  it  must  have  required  a  climate  suffi- 
ciently warm  to  insure  that  the  rivers  were  not  frozen  over  in  the 
winter;  but  it  was  probably  a  migratory  animal,  and  its  occur- 
rence may  be  accounted  for  by  this.  The  Woolly  Rhinoceros 
and  the  Mammoth  are  known  with  certainty  to  have  been  pro- 
tected with  a  thick  covering  of  wool  and  hair  ;  and  their  ex- 
tension northwards  need  not  necessarily  have  been  limited  by 
anything  except  the  absence  of  a  sufficiently  luxuriant  vege- 
tation to  afford  them  food.  The  great  American  Mastodon, 
though  not  certainly  known  to  have  possessed  a  hairy  covering, 
has  been  shown  to  have  lived  upon  the  shoots  of  Spruce  and 
Firs,  trees  characteristic  of  temperate  regions — as  shown  by  the 
undigested  food  which  has  been  found  with  its  skeleton,  oc- 
cupying the  place  of  the  stomach.  The  Lions  and  Hyaenas, 
again,  as  shown  by  Professor  Boyd  Dawkins,  do  not  indicate 
necessarily  a  warm  climate.  Wherever  a  sufficiency  of  her- 
bivorous animals  to  supply  them  with  food  can  live,  there  they 
can  live  also ;  and  they  have  therefore  no  special  bearing  upon 
the  question  of  climate.  After  a  review  of  the  whole  evidence, 
Professor  Dawkins  concludes  that  the  nearest  approach  at  the 
present  day  to  the  Post-Pliocene  climate  of  Western  Europe 
is  to  be  found  in  the  climate  of  the  great  Siberian  plains  which 
stretch  from  the  Altai  Mountains  to  the  Frozen  Sea.  "Covered 


FAUNA   OF   THE   POST-PLIOCENE.  363 

by  impenetrable  forests,  for  the  most  part  of  Birch,  Poplar, 
Larch,  and  Pines,  and  low  creeping  dwarf  Cedars,  they  present 
every  gradation  in  climate  from  the  temperate  to  that  in  which 
the  cold  is  too  severe  to  admit  of  the  growth  of  trees,  which 
decrease  in  size  as  the  traveller  advances  northwards,  and  are 
replaced  by  the  grey  mosses  and  lichens  that  cover  the  low 
marshy  'tundras.'  The  maximum  winter  cold,  registered  by 
Admiral  Von  Wrangel  at  Nishne  Kolymsk,  on  the  banks  of 
the  Kolyma,  is — 65°  in  January.  'Then  breathing  becomes 
difficult ;  the  Reindeer,  that  citizen  of  the  Polar  region,  with- 
draws to  the  deepest  thicket  of  the  forest,  and  stands  there 
motionless  as  if  deprived  of  life ; '  and  trees  burst  asunder  with 
the  cold.  Throughout  this  area  roam  Elks,  Black  Bears, 
Foxes,  Sables,  and  Wolves,  that  afford  subsistence  to  the 
Jakutian  and  Tungusian  fur-hunters.  In  the  northern  part 
countless  herds  of  Reindeer,  Elks,  Foxes,  and  Wolverines 
make  up  for  the  poverty  of  vegetation  by  the  rich  abundance 
of  animal  life.  '  Enormous  flights  of  Swans,  Geese,  and  Ducks 
arrive  in  the  spring,  and  seek  deserts  where  they  may  moult 
and  build  their  nests  in  safety.  Pcarmigans  run  in  troops 
amongst  the  bushes  :  little  Snipes  are  busy  along  the  brooks 
and  in  the  morasses  ;  the  social  Crows  seek  the  neighbourhood 
of  new  habitations ;  and  when  the  sun  shines  in  spring,  one 
may  even  sometimes  hear  the  cheerful  note  of  the  Finch,  and 
in  autumn  that  of  the  Thrush.'  Throughout  this  region  of 
woods,  a  hardy,  middle-sized  breed  of  horses  lives  under  the 
mastership  and  care  of  man,  and  is  eminently  adapted  to  bear 
the  severity  of  the  climate.  .  .  .  The  only  limit  to  their 
northern  range  is  the  difficulty  of  obtaining  food.  The  severity 
of  the  winter  through  the  southern  portion  of  this  vast  wooded 
area  is  almost  compensated  for  by  the  summer  heat  and  its 
marvellous  effect  on  vegetation."— (Dawkins,  '  Monograph  of 
Pleistocene  Mammalia.') 

Finally,  a  few  words  must  be  said  as  to  the  occurrence  of  the 
remains  of  Man  in  Post-Pliocene  deposits.  That  Man  existed 
in  Western  Europe  and  in  Britain  during  the  Post- Pliocene 
period,  is  placed  beyond  a  doubt  by  the  occurrence  of  his  bones 
in  deposits  of  this  age,  along  with  the  much  more  frequent 
occurrence  of  implements  of  human  manufacture.  .  At  what 
precise  point  of  time  during  the  Post-Pliocene  period  he  first 
made  his  appearance  is  still  a  matter  of  conjecture.  Recent 
researches  would  render  it  probable  that  the  early  inhabitants 
of  Britain  and  Western  Europe  were  witnesses  of  the  stupend- 
ous phenomena  of  the  Glacial  period  ;  but  this  cannot  be  said 
to  have  been  demonstrated.  That  Man  existed  in  these 


364  HISTORICAL   PALEONTOLOGY. 

regions  during  the  Post-Glacial  division  of  Post-Pliocene  time 
cannot  be  doubted  for  a  moment.  As  to  the  physical  peculi- 
arities of  the  ancient  races  that  lived  with  the  Mammoth  and 
the  Woolly  Rhinoceros,  little  is  known  compared  with  what 
we  may  some  day  hope  to  know.  Such  information  as  we 
have,  however,  based  principally  on  the  skulls  of  the  Engis, 
Neanderthal,  Cro-Magnon,  and  Bruniquel  caverns,  would  lead 
to  the  conclusion  that  Post-Pliocene  Man  was  in  no  respect 
inferior  in  his  organisation  to,  or  less  highly  developed  than, 
many  existing  races.  All  the  known  skulls  of  this  period,  with 
the  single  exception  of  the  Neanderthal  cranium,  are  in  all 
respects  average  and  normal  in  their  characters  ;  and  even  the 
Neanderthal  skull  possessed  a  cubic  capacity  at  least  equal  to 
that  of  some  existing  races.  The  implements  of  Post-Pliocene 
Man  are  exclusively  of  stone  or  bone ;  and  the  former  are 
invariably  of  rude  shape  and  undressed.  These  "palaeolithic" 
tools  (Gr.  palaios,  ancient ;  lithos,  stone)  point  to  a  very  early 
condition  of  the  arts ;  since  the  men  of  the  earlier  portion 
of  the  Recent  period,  though  likewise  unacquainted  with  the 
metals,  were  in  the  habit  of  polishing  or  dressing  the  stone 
implements  which  they  fabricated. 

It  is  impossible  here  to  enter  further  into  this  subject ;  and 
it  would  be  useless  to  do  so  without  entering  as  well  into  a 
consideration  of  the  human  remains  of  the  Recent  period — a 
period  which  lies  outside  the  province  of  the  present  work.  So 
far  as  Post-Pliocene  Man  is  concerned,  the  chief  points  which 
the  palaeontological  student  has  to  remember  have  been  else- 
where summarised  by  the  author  as  follows  :— 

1.  Man  unquestionably  existed  during  the  later  portion  of 
what  Sir  Charles  Lyell  has  termed  the  "Post-Pliocene"  period. 
In  other  words,  Man's  existence  dates  back  to  a  time  when 
several  remarkable  Mammals,  previously  mentioned,  had  not 
yet  become  extinct ;   but  he  does  not  date  back  to  a  time 
anterior  to  the  present  Molluscan  fauna. 

2.  The  antiquity  of  the   so-called  Post-Pliocene  period  is 
a  matter  which  must  be  mainly  settled   by  the  evidence  of 
Geology  proper,  and  need  not  be  discussed  here. 

3.  The    extinct    Mammals   with   which    man    coexisted    in 
Western  Europe  are  mostly  of  large  size,  the  most  important 
being  the  Mammoth  (Elephas  primigenius],  the  Woolly  Rhino- 
ceros (Rhinoceros  tichorhinus),  the  Cave-lion  (Felis  spelcea],  the 
C&ve-hy&na..(&yanaspe/aa),  and  the  Cave-bear  ( Ursus  spelaus). 
We  do  not  know  the  causes  which    led  to  the  extinction  of 
these  Mammals  ;  but  we   know  that  hardly  any  Mammalian 
species  has  become  extinct  during  the  historical  period. 


FAUNA   OF   THE  POST-PLIOCENE.  365 

4.  The  extinct  Mammals  with  which  man  coexisted  are  re- 
ferable in  many  cases  to  species  which  presumably  required  a 
very  different  climate  to  that  now  prevailing  in  Western  Europe. 
How  long  a  period,  however,  has  been  consumed  in  the  bring- 
ing about  of  the  climatic  changes  thus  indicated,  we  have  no 
means  of  calculating  with  any  approach  to  accuracy. 

5.  Some  of  the  deposits  in  which  the  remains  of  man  have 
been  found  associated  with  the  bones  of  extinct  Mammals,  are 
such  as  to  show  incontestably  that  great  changes  in  the  phy- 
sical geography  and  surface-configuration  of  Western  Europe 
have  taken  place  since  the  period  of  their  accumulation.     We 
have,  however,  no  means  at  present  of  judging  of  the  lapse  of 
time  thus  indicated  except  by  analogies  and  comparisons  which 
may  be  disputed. 

6.  The  human  implements  which   are  associated  with  the 
remains  of  extinct  Mammals,  themselves  bear  evidence  of  an 
exceedingly  barbarous  condition  of  the  human  species.     Post- 
Pliocene  or  "  Palaeolithic  "  Man  was  clearly  unacquainted  with 
the  use  of  any  of  the  metals.     Not  only  so,  but  the  workman- 
ship of  these  ancient  races  was  much  inferior  to  that  of  the 
later  tribes,  who  were  also  ignorant  of  the  metals,  and  who 
also  used  nothing  but  weapons  and  tools  of  stone,  bone,  &c. 

7.  Lastly,  it  is  only  with  the  human  remains  of  the  Post- 
Pliocene  period  that  the  palaeontologist  proper  has  to  deal. 
When  we  enter  the  "  Recent"  period,  in  which  the  remains  of 
Man  are  associated  with  those  of  existing  species  of  Mammals, 
we  pass  out  of  the  region  of  pure  palaeontology  into  the  do- 
main of  the  Archaeologist  and  the  Ethnologist. 


LITERATURE. 

The  following  are  some  of  the  principal  works  and  memoirs  to  which 
the  student  may  refer  for  information  as  to  the  Post-Pliocene  deposits  and 
the  remains  which  they  contain,  as  well  as  to  the  primitive  races  of  man- 
kind : — 

(i)   'Elements  of  Geology.'     Lyell. 

^2)   '  Antiquity  of  Man.'     Lyell. 

(3)  '  Palgeontological  Memoirs.'     Falconer. 

(4)  '  The  Great  Ice-age.'     James  Geikie. 

(5)  '  Manual  of  Palaeontology.'     Owen. 

(6)  '  British  Fossil  Mammals  and  Birds.'     Owen. 

(7)  'Cave-Hunting.'     Boyd  Dawkins. 

(8)  '  Prehistoric  Times.'     Lubbock. 

(9)  '  Ancient  Stone  Implements.'     Evans. 
(10)   '  Prehistoric  Man.'     Daniel  Wilson. 

(u)   'Prehistoric  Races  of  the  United  States.'     Foster. 
(12)   'Manual  of  Geology.'     Dana. 

25 


366  HISTORICAL  PAL/EONTOLOGY. 

(13)  'Monograph  of    Pleistocene   Mammalia'    (Palaeontographical   So- 

ciety).     Boycl  Dawkins  and  Sanford. 

(14)  'Monograph  of  the  Post-Tertiary  Entomostraca  of  Scotland,  &c., 

with  an  Introduction  on  the  Post-Tertiary  Deposits  of  Scotland ' 
(Ibid.)     G.  S.  Brady,  H.  \V.  Crosskey,  and  D.  Robertson. 

(15)  "Reports   on   Kent's   Cavern"  —  'British    Association    Reports.' 

Pengelly. 

(16)  "Reports  on  the  Victoria  Cavern,    Settle" — 'British   Association 

Reports.'     Tiddeman. 

(17)  '  Ossemens  Fossiles.'     Cuvier. 

(18)  '  Reliquiae  Diluvianre. '     Buckland. 

(19)  "Fossil    Mammalia" — 'Zoology   of  the   Voyage  of  the    Beagle.' 

Owen. 

(20)  *  Description  of  the  Tooth  and  Part  of  the  Skeleton  of  the  Glyp- 

todonS     Owen. 

(21)  "  Memoir  on  the  Extinct  Sloth  Tribe  of  North  America  " — '  Smith- 

sonian Contributions  to  Knowledge.'     Leidy. 

(22)  "  Report  on  Extinct  Mammals  of  Australia " — 'British  Association/ 

1844.     Owen. 

(23)  'Description  of  the  Skeleton  of  an  Extinct  Gigantic  Sloth  (Mylodon 

robustus).'     Owen. 

(24)  "Affinities  and  Probable  Habits  of  Thylacoleo" — 'Quart.  Journ. 

Geol.  Soc.,'  vol.  xxiv.     Flower. 

(25)  '  Prodromus  of  the  Palaeontology  of  Victoria.'     M'Coy. 

(26)  '  Les  Ossemens  Fossiles  des  Cavernes  de  Liege.'     Schmerling. 

(27)  (  Die  Fauna  der  Pfahlbauten  in  der  Schweiz.'     Riitimeyer. 

(28)  "  Extinct  and  Existing  Bovine  Animals  of  Scandinavia" — '  Annals 

of  Natural  History,'  ser.  2,  vol.  iv.,  1849.     Nilsson. 

(29)  'Man's  Place  in  Nature.'     Huxley. 

(30)  'Les  Temps  Antehistoriques  en  Belgique.'     Dupont. 

(31)  "Classification  of  the  Pleistocene  Strata  of  Britain  and  the  Conti- 

nent"— 'Quart.  Journ.  Geol.  Soc., 'vol.  xxviii.     Boyd  Dawkins. 

(32)  '  Distribution   of  the  Post  -  Glacial  Mammalia '   (Ibid. ),    vol.   xxv. 

Boyd  Dawkins. 

(33)  'On   British  Fossil    Oxen'    (Ibid.),   vols.   xxii.    and   xxiii.       Boyd 

Dawkins. 

(34)  'British   Prehistoric   Mammals'   (Congress  of  Prehistoric   Archae- 

ology, 1868).     Boyd  Dawkins. 

(35)  'Reliquiae  Aquitanicae.'     Lartet  and  Christy. 

(36)  'Zoologie  et  Paleontologie  Francaises.'     Gervais. 

(37)  'Notes  on  the  Post- Pliocene  Geology  of  Canada.'     Tawson. 

(38)  "  On  the  Connection  between  the  existing  Fauna  and  Flora  ot  Great 

Britain  and  certain  Geological  Changes" — 'Mem.  Geol.  Survey.' 
Edward  Forbes. 

(39)  'Cavern-Researches.'     M'Enery.     Edited  by  Vivian. 

(40)  "Quaternary   Gravels" — 'Quart.    Journ.    Geol.    Soc.,'    vol.    xxv. 

Tylor. 


SUCCESSION    OF    LIFE   UPON   THE  GLOBE.         367 

CHAPTER    XXIII. 
THE  SUCCESSION  OF  LIFE  UPON  THE  GLOBE. 

In  conclusion,  it  may  not  be  out  of  place  if  we  attempt  to 
summarise,  in  the  briefest  possible  manner,  some  of  the  prin- 
cipal results  which  may  be  deduced  as  to  the  succession  of 
life  upon  the  earth  from  the  facts  which  have  in  the  preceding 
portion  of  this  work  been  passed  in  review.  That  there  was 
a  time  when  the  earth  was  void  of  life  is  universally  admitted, 
though  it  may  be  that  the  geological  record  gives  us  no  direct 
evidence  of  this.  That  the  globe  of  to-day  is  peopled  with 
innumerable  forms  of  life  whose  term  of  existence  has  been, 
for  the  most  part,  but  as  it  were  of  yesterday,  is  likewise  an 
assertion  beyond  dispute.  Can  we  in  any  way  connect  the 
present  with  the  remote  past,  and  can  we  indicate  even  im- 
perfectly the  conditions  and  laws  under  which  the  existing 
order  was  brought  about?  The  long  series  of  fossiliferous 
deposits,  with  their  almost  countless  organic  remains,  is  the 
link  between  what  has  been  and  what  is ;  and  if  any  answer 
to  the  above  question  can  be  arrived  at,  it  will  be  by  the 
careful  and  conscientious  study  of  the  facts  of  Palaeontology. 
In  the  present  state  of  our  knowledge,  it  may  be  safely  said 
that  anything  like  a  dogmatic  or  positive  opinion  as  to  the 
precise  sequence  of  living  forms  upon  the  globe,  and  still 
more  as  to  the  manner  in  which  this  sequence  may  have  been 
brought  about,  is  incapable  of  scientific  proof.  There  are, 
however,  certain  general  deductions  from  the  known  facts 
which  may  be  regarded  as  certainly  established. 

In  the  first  place,  it  is  certain  that  there  has  been  a  succession 
of  life  upon  the  earth,  different  specific  and  generic  types  suc- 
ceeding one  another  in  successive  periods.  It  follows  from 
this,  that  the  animals  and  plants  with  which  we  are  familiar  as 
living,  were  not  always  upon  the  earth,  but  that  they  have  been 
preceded  by  numerous  races  more  or  less  differing  from  them. 
What  is  true  of  the  species  of  animals  and  plants,  is  true  also 
of  the  higher  zoological  divisions ;  and  it  is,  in  the  second 
place,  quite  certain  that  there  has  been  a  similar  succession  in 
the  order  of  appearance  of  the  primary  groups  ("  sub-king- 
doms," "classes,"  &c.)  of  animals  and  vegetables.  These 
great  groups  did  not  all  come  into  existence  at  once,  but  they 
made  their  appearance  successively.  It  is  true  that  we  can- 
not be  said  to  be  certainly  acquainted  with  the  first  absolute 


368  HISTORICAL    PALEONTOLOGY. 

appearance  of  any  great  group  of  animals.  No  one  dare 
assert  positively  that  the  apparent  first  appearance  of  Fishes 
in  the  Upper  Silurian  is  really  their  first  introduction  upon  the 
earth  :  indeed,  there  is  a  strong  probability  against  any  such 
supposition.  To  whatever  extent,  however,  future  discoveries 
may  push  back  the  first  advent  of  any  or  of  all  of  the  great 
groups  of  life,  there  is  no  likelihood  that  anything  will  be  found 
out  which  will  materially  alter  the  relative  succession  of  these 
groups  as  at  present  known  to  us.  It  is  not  likely,  for 
example,  that  the  future  has  in  store  for  us  any  discovery  by 
which  it  would  be  shown  that  Fishes  were  in  existence  before 
Molluscs,  or  that  Mammals  made  their  appearance  before 
Fishes.  The  sub-kingdoms  of  Invertebrate  animals  were  all 
represented  in  Cambrian  times — and  it  might  therefore  be  in- 
ferred that  these  had  all  come  simultaneously  into  existence ; 
but  it  is  clear  that  this  inference,  though  incapable  of  actual 
disproof,  is  in  the  last  degree  improbable.  Anterior  to  the 
Cambrian  is  the  great  series  of  the  Laurentian,  which,  owing 
to  the  metamorphism  to  which  it  has  been  subjected,  has  so 
far  yielded  but  the  singular  Eozoon.  We  may  be  certain, 
however,  that  others  of  the  Invertebrate  sub-kingdoms  besides 
the  Protozoa  were  in  existence  in  the  Laurentian  period ;  and 
we  may  infer  from  known  analogies  that  they  appeared  suc- 
cessively, and  not  simultaneously. 

When  we  come  to  smaller  divisions  than  the  sub -king- 
doms— such  as  classes,  orders,  and  families — a  similar  suc- 
cession of  groups  is  observable.  The  different  classes  of 
n.ny  given  sub-kingdom,  or  the  different  orders  of  any  given 
class,  do  not  make  their  appearance  together  and  all  at  once, 
but  they  are  introduced  upon  the  earth  in  succession.  More 
than  this,  the  different  classes  of  a  sub-kingdom,  or  the  differ- 
ent orders  of  a  class,  in  the  main  succeed  one  another  in  the 
relative  order  of  their  zoological  rank — the  lower  groups  appear- 
ing first  and  the  higher  groups  last.  It  is  true  that  in  the 
Cambrian  formation — the  earliest  series  of  sediments  in  which 
fossils  are  abundant — we  find  numerous  groups,  some  very 
low,  others  very  high,  in  the  zoological  scale,  which  appear 
to  have  simultaneously  flashed  into  existence.  For  reasons 
stated  above,  however,  we  cannot  accept  this  appearance  as 
real ;  and  we  must  believe  that  many  of  the  Cambrian  groups 
of  animals  really  came  into  being  long  before  the  commence- 
ment of  the  Cambrian  period.  At  any  rate,  in  the  long  series 
of  fossiliferous  deposits  of  later  date  than  the  Cambrian  the 
above-stated  rule  holds  good  as  a  broad  generalisation — that 
the  lower  groups,  namely,  precede  the  higher  in  point  of  time; 


SUCCESSION    OF   LIFE    UPON    THE   GLOBE.         569 

and  though  there  are  apparent  exceptions  to  the  rule,  there 
are  none  of  such  a  nature  as  not  to  admit  of  explanation. 
Some  of  the  leading  facts  upon  which  this  generalisation  is 
founded  will  be  enumerated  immediately ;  but  it  will  be  well, 
in  the  first  place,  to  consider  briefly  what  we  precisely  mean 
when  we  speak  of  "  higher"  and  "  lower"  groups. 

It  is  well  known  that  naturalists  are  in  the  habit  of  "  clas- 
sifying" the  innumerable  animals  which  now  exist  upon  the 
globe ;  or,  in  other  words,  of  systematically  arranging  them  into 
groups.  The  precise  arrangement  adopted  by  one  naturalist 
may  differ  in  minor  details  from  that  adopted  by  another;  but 
all  are  agreed  as  to  the  fundamental  points  of  classification, 
and  all,  therefore,  agree  in  placing  certain  groups  in  a  certain 
sequence.  What,  then,  is  the  principle  upon  which  this 
sequence  is  based  ?  Why,  for  example,  are  the  Sponges  placed 
below  the  Corals;  these  below  the  Sea-urchins;  and  these,  again, 
below  the  Shell-fish?  Without  entering  into  a  discussion  of 
the  principles  of  zoological  classification,  which  would  here  be 
out  of  place,  it  must  be  sufficient  to  say  that  the  sequence  in 
question  is  based  upon  the  rclativt  type  of  organisation  of  the 
groups  of  animals  classified.  The  Corals  are  placed  above  the 
Sponges  upon  the  ground  that,  regarded  as  a  whole,  the  //£;* 
or  type  of  structure  of  a  Corai  is  more  complex  than  that  of  a 
Sponge.  It  is  not  in  the  slightest  degree  that  the  Sponge  is  in 
any  respect  less  highly  organised  or  less  perfect,  as  a  Sponge. 
than  is  the  Coral  as  a  Coral.  Each  is  equally  perfect  in  its 
own  way ;  but  the  structural  pattern  of  the  Coral  is  the  highest, 
and  therefore  it  occupies  a  higher  place  in  the  zoological  scale. 
It  is  upon  this  principle,  then,  that  the  primary  subdivisions 
of  the  animal  kingdom  (the  so-called  "sub-kingdoms")  are 
arranged  in  a  certain  order.  Coming,  again,  to  the  minor 
subdivisions  (classes,  orders,  &c.)  of  each  sub-kingdom,  we 
find  a  different  but  entirely  analogous  principle  employed  as  a 
means  of  classification.  The  numerous  animals  belonging  to 
any  given  sub-kingdom  are  formed  upon  the  same  fundamental 
plan  of  structure ;  but  they  nevertheless  admit  of  being  ar- 
ranged in  a  regular  series  of  groups.  All  the  Shell-fish,  for 
example,  are  built  upon  a  common  plan,  this  plan  representing 
the  ideal  Mollusc ;  but  there  are  at  the  same  time  various 
groups  of  the  Mollusca,  and  these  groups  admit  of  an  arrange- 
ment in  a  given  sequence.  The  principle  adopted  in  this  case 
is  simply  of  the  relative  elaboration  of  the  common  type.  The 
Oyster  is  built  upon  the  same  ground-plan  as  the  Cuttle-fish;  but 
this  plan  is  carried  out  with  much  greater  elaboration,  and  with 
many  more  complexities^  in  the  latter  than  in  the  former:  and 


3/0  HISTORICAL   PALEONTOLOGY. 

in  accordance  with  this,  the  CepJi.ilopoda  constitute  a  higher 
group  than  the  Bivalve  Shell-fish.  As  in  the  case  of  superiority 
of  structural  type,  so  in  this  case  also,  it  is  not  in  the  least  that 
the  Oyster  is  an  imperfect  animal.  On  the  contrary,  it  is  just 
as  perfectly  adapted  by  its  organisation  to  fill  its  own  sphere 
and  to  meet  the  exigencies  of  its  own  existence  as  is  the 
Cuttle-fish ;  but  the  latter  lives  a  life  which  is,  physiologically, 
higher  than  the  former,  and  its  organisation  is  correspondingly 
increased  in  complexity. 

This  being  understood,  it  may  be  repeated  that,  in  the 
main,  the  succession  of  life  upon  the  globe  in  point  of  time 
has  corresponded  with  the  relative  order  of  succession  of  the 
great  groups  of  animals  in  zoological  rank ;  and  some  of  the 
more  striking  examples  of  this  may  be  here  alluded  to. 
Amongst  the  Echinoderms,  for  instance,  the  two  orders  gen- 
erally admitted  to  be  the  "  lowest "  in  the  zoological  scale — 
namely,  the  Crinoids  and  the  Cystoids — are  likewise  the  oldest, 
both  appearing  in  the  Cambrian,  the  former  slowly  dying  out 
as  we  approach  the  Recent  period,  and  the  latter  disappearing 
wholly  before  the  close  of  the  Palaeozoic  period.  Amongst  the 
Crustaceans,  the  ancient  groups  of  the  Trilobites,  Ostracodes, 
Phyllopods,  Eurypterids,  and  Limuloids,  some  of  which  exist 
at  the  present  day,  are  all  "  low  "  types ;  whereas  the  highly- 
organised  Decapods  do  not  make  their  appearance  till  near  the 
close  of  the  Palaeozoic  epoch,  and  they  do  not  become  abun- 
dant till  we  reach  Mesozoic  times.  Amongst  the  Mollusca, 
those  Bivalves  which  possess  breathing-tubes  (the  "siphonate 
Bivalves)  are  generally  admitted  to  be  higher  than  those  which 
are  destitute  of  these  organs  (the  "asiphonale"  Bivalves);  and 
the  latter  are  especially  characteristic  of  the  Palaeozoic  period, 
whilst  the  former  abound  in  Mesozoic  and  Kainozoic  forma- 
tions. Similarly,  the  Univalves  with  breathing-tubes  and  a 
corresponding  notch  in  the  mouth  of  the  shell  ("siphonosto- 
matous"  Univalves)  are  regarded  as  higher  in  the  scale  than 
the  round-mouthed  vegetable-eating  Sea-snails,  in  which  no 
respiratory  siphons  exist  ("holostomatous"  Univalves);  but 
the  latter  abound  in  the  Palaeozoic  rocks — whereas  the  former 
do  not  make  their  appearance  till  the  Jurassic  period,  and 
their  higher  groups  do  not  seem  to  have  existed  till  the  close 
of  the  Cretaceous.  The  Cephalopods,  again — the  highest  of  all 
the  groups  of  Mollusca — are  represented  in  the  Palaeozoic 
rocks  exclusively  by  Tetrabranchiate  forms,  which  constitute 
the  lowest  of  the  two  orders  of  this  class ;  whereas  the  more 
highly  specialised  Dibranchiates  do  not  make  their  appearance 
till  the  commencement  of  the  Mesozoic.  The  Palaeozoic 


SUCCESSION    OF   LIFE   UPON   THE   GLOBE.         371 

Tetrabranchiates,  also,  are  of  a  much  simpler  type  than  the 
highly  complex  Ammonitida  of  the  Mesozoic. 

Similar  facts  are  observable  amongst  the  Vertebrate  animals. 
The  Fishes  are  the  lowest  class  of  Vertebrates,  and  they  are 
the  first  to  appear,  their  first  certain  occurrence  being  in  the 
Upper  Silurian  ;  whilst,  even  if  the  Lower  Silurian  and  Upper 
Cambrian  "  Conodonts  "  were  shown  to  be  the  teeth  of  Fishes, 
there  would  still  remain  the  enormously  long  periods  of  the 
Laurentian  and  Lower  Cambrian,  during  which  there  were  In- 
vertebrates, but  no  Vertebrates.  The  Amphibians,  the  next 
class  in  zoological  order,  appears  later  than  the  Fishes,  and 
is  not  represented  till  the  Carboniferous;  whilst  its  highest 
group  (that  of  the  Frogs  and  Toads)  does  not  make  its  entrance 
upon  the  scene  till  Tertiary  times  are  reached.  The  class  of 
the  Reptiles,  again,  the  next  in  order,  does  not  appear  till 
the  Permian,  and  therefore  not  till  after  Amphibians  of  very 
varied  forms  had  been  in  existence  for  a  protracted  period. 
The  Birds  seem  to  be  undoubtedly  later  than  the  Reptiles ; 
but,  owing  to  the  uncertainty  as  to  the  exact  point  of  their  first 
appearance,  it  cannot  be  positively  asserted  that  they  pre- 
ceded Mammals,  as  they  should  have  done.  Finally,  the 
Mesozoic  types  tf  Mammals  are  mainly,  if  not  exclusively, 
referable  to  the  Marsupials,  one  of  the  lowest  orders  of  the 
class ;  whilst  the  higher  orders  of  the  "  Placental "  Quadrupeds 
are  not  with  certainty  known  to  have  existed  prior  to  the  com- 
mencement of  the  Tertiary  period. 

Facts  of  a  very  similar  nature  are  offered  by  the  succession 
of  Plants  upon  the  globe.  Thus  the  vegetation  of  the  Palaeo- 
zoic period  consisted  principally  of  the  lowly-organised  groups 
of  the  Cryptogamous  or  Flowerless  plants.  The  Mesozoic 
formations,  up  to  the  Chalk,  are  especially  characterised  by  the 
naked-seeded  Flowering  plants — the  Conifers  and  the  Cycads; 
whilst  the  higher  groups  of  the  Angiospermous  Exogens  and 
Monocotyledons  characterise  the  Upper  Cretaceous  and  Ter- 
tiary rocks. 

Facts  of  the  above  nature — and  they  could  be  greatly  multi- 
plied— seem  to  point  clearly  to  the  existence  of  some  law  of 
progression,  though  we  certainly  are  not  yet  in  a  position  to 
formulate  this  law,  or  to  indicate  the  precise  manner  in  which 
it  has  operated.  Two  considerations,  also,  must  not  be  over- 
looked. In  the  first  place,  there  are  various  groups,  some  of 
them  highly  organised,  which  make  their  appearance  at  an  ex- 
tremely ancient  date,  but  which  continue  throughout  geological 
time  almost  unchanged,  and  certainly  unprogressive.  Many  of 
these  "  persistent  types  "  are  known — such  as  various  of  the 


3/2  HISTORICAL  PALEONTOLOGY. 

Foranttiiifera,  the  Ltngula,  the  Nautili,  &c. ;  and  they  indicate 
that  under  given  conditions,  at  present  unknown  to  us,  it  is 
possible  for  a  life-form  to  subsist  for  an  almost  indefinite  period 
without  any  important  modification  of  its  structure.  In  the 
second  place,  whilst  the  facts  above  mentioned  point  to  some 
general  law  of  progression  of  the  great  zoological  groups,  it 
cannot  be  asserted  that  the  primeval  types  of  any  given  group 
are  necessarily  "  lower,"  zoologically  speaking,  than  their 
modern  representatives.  Nor  does  this  seem  to  be  at  all 
necessary  for  the  establishment  oC  the  law  in  question.  It 
cannot  be  asserted,  for  example,  that  the  Ganoid  and  Placoid 
Fishes  of  the  Upper  Silurian  are  in  themselves  less  highly 
organised  than  their  existing  representatives  ;  nor  can  it  even 
be  asserted  that  the  Ganoid  and  Placoid  orders  are  low  groups 
of  the  class  Pisces.  On  the  contrary,  they  are  high  groups; 
but  then  it  must  be  remembered  that  these  are  probably  not 
really  the  first  Fishes,  and  that  if  we  meet  with  Fishes  at  some 
future  time  in  the  Lower  Silurian  or  Cambrian,  these  m?y 
easily  prove  to  be  representatives  of  the  lower  orders  of  the 
class.  This  question  cannot  be  further  entered  into  here,  as 
its  discussion  could  be  carried  out  to  an  almost  unlimited 
length ;  but  whilst  there  are  facts  pointing  both  ways,  it 
appears  that  at  present  we  are  not  justified  in  asserting  that  the 
earlier  types  of  each  group — so  far  as  these  are  known  to  us, 
or  really  are  without  predecessors — are  necessarily  or  invariably 
more  "  degraded "  or  "  embryonic "  in  their  structure  than 
their  more  modern  representatives. 

It  remains  to  consider  very  briefly  how  far  Palaeontology 
supports  the  doctrine  of  "  Evolution,"  as  it  is  called  ;  and  this, 
too,  is  a  question  of  almost  infinite  dimensions,  which  can  but 
be  glanced  at  here.  Does  Palaeontology  teach  us  that  the 
almost  innumerable  kinds  of  animals  and  plants  which  we 
know  to  have  successively  flourished  upon  the  earth  in  past 
times  were  produced  separately  and  wholly  independently  of 
each  other,  at  successive  periods?  or  does  it  point  to  the 
theory  that  a  large  number  of  these  supposed  distinct  forms 
have  been  in  reality  produced  by  the  slow  modification  of  a 
comparatively  small  number  of  primitive  types  ?  Upon  the 
whole,  it  must  be  unhesitatingly  replied  that  the  evidence  of 
Palaeontology  is  in  favour  of  the  view  that  the  succession  of 
life-forms  upon  the  globe  has  been  to  a  large  extent  regulated 
by  some  orderly  and  constantly-acting  law  of  modification  and 
evolution.  Upon  no  other  theory  can  we  comprehend  how 
the  fauna  of  any  given  formation  is  more  closely  related  to 
that  of  the  formation  next  below  in  the  series,  and  to  that  of 


SUCCESSION  OF  LIFE  UPON  THE  GLOBE.       373 

the  formation  next  above,  than  to  that  of  any  other  series  of 
deposits.  Upon  no  other  view  can  we  comprehend  why  the 
Post-Tertiary  Mammals  of  South  America  should  consist  prin- 
cipally of  Edentates,  Llamas,  Tapirs,  Peccaries,  Platyrhine 
Monkeys,  and  other  forms  now  characterising  this  continent ; 
whilst  those  of  Australia  should  be  wholly  referable  to  the 
order  of  Marsupials.  On  no  other  view  can  we  explain  the 
common  occurrence  of  "  intermediate  "  or  "  transitional  " 
forms  of  life,  filling  in  the  gaps  between  groups  now  widely 
distinct. 

On  the  other  hand,  there  are  facts  which  point  clearly  to  the 
existence  of  some  law  other  than  that  of  evolution,  and  pro- 
bably of  a  deeper  and  more  far-reaching  character.  Upon  no 
theory  of  evolution  can  we  find  a  satisfactory  explanation  for 
the  constant  introduction  throughout  geological  time  of  new 
forms  of  life,  which  do  not  appear  to  have  been  preceded  by 
pre-existent  allied  types.  The  Graptolites  and  Trilobites  have 
no  known  predecessors,  and  leave  no  known  successors.  The 
Insects  appear  suddenly  in  the  Devonian,  and  the  Arachnides 
and  Myriapods  in  the  Carboniferous,  under  well-differentiated 
and  highly-specialised  types.  The  Dibranchiate  Cephalopods 
appear  with  equal  apparent  suddenness  in  the  older  Mesozoic 
deposits,  and  no  known  type  of  the  Palaeozoic  period  can  be 
pointed  to  as  a  possible  ancestor,  The  Hippuritida  of  the 
Cretaceous  burst  into  a  varied  life  to  all  appearance  almost 
immediately  after  their  first  introduction  into  existence.  The 
wonderful  Dicotyledonous  flora  of  the  Upper  Cretaceous 
period  similarly  surprises  us  without  any  prophetic  annuncia- 
tion from  the  older  Jurassic. 

Many  other  instances  could  be  given  ;  but  enough  has  been 
said  to  show  that  there  is  a  good  deal  to  be  said  on  both  sides, 
and  that  the  problem  is  one  environed  with  profound  difficul- 
ties. One  point  only  seems  now  to  be  universally  conceded, 
and  that  is,  that  the  record  of  life  in  past  time  is  not  interrupted 
by  gaps  other  than  those  due  to  the  necessary  imperfections  of 
the  fossiliferous  series,  to  the  fact  that  many  animals  are  in- 
capable of  preservation  in  a  fossil  condition,  or  to  other  causes 
of  a  like  nature.  All  those  who  are  entitled  to  speak  on  this 
head  are  agreed  that  the  introduction  of  new  and  the  destruc- 
tion of  old  species  have  been  slow  and  gradual  processes,  in  no 
sense  of  the  term  "  catastrophistic."  Most  are  also  willing  to 
admit  that  "  Evolution "  has  taken  place  in  the  past,  to  a 
greater  or  less  extent,  and  that  a  greater  or  less  number  of  so- 
called  species  of  fossil  animals  are  really  the  modified  descend- 
ants of  pre-existent  forms.  How  this  process  of  evolution  has 


374  HISTORICAL   PALAEONTOLOGY. 

been  effected,  to  what  extent  it  has  taken  place,  under  what 
conditions  and  laws  it  has  been  carried  out,  and  how  far  it 
may  be  regarded  as  merely  auxiliary  and  supplemental  to  some 
deeper  law  of  change  and  progress,  are  questions  to  which,  in 
spite  of  the  brilliant  generalisations  of  Darwin,  no  satisfactory 
answer  can  as  yet  be  given.  In  the  successful  solution  of  this 
problem — if  soluble  with  the  materials  available  to  our  hands 
— will  lie  the  greatest  triumph  that  Palaeontology  can  hope  to 
attain  ;  and  there  is  reason  to  think  that,  thanks  to  the  guiding- 
clue  afforded  by  the  genius  of  the  author  of  the  '  Origin  of 
Species,'  we  are  at  least  on  the  road  to  a  sure,  though  it  may 
be  a  far-distant,  victory. 


APPENDIX. 


TABULAR  VIEW  OF  THE  CHIEF  DIVISIONS 
OF  THE  ANIMAL  KINGDOM. 

(Extinct  groups  are  marked  with  an  asterisk.     Groups  not  represented 
at  all  as  fossils  are  marked  with  two  asterisks.) 

INVERTEBRATE    ANIMALS. 

SUB-KINGDOM  I. — PROTOZOA. 

Animal  simple  or  compound  ;  body  composed  of  "sarcode,"  not  de- 
finitely segmented  ;  no  nervous  system;  and  no  digestive  apparatus,  beyond 
occasionally  a  mouth  and  gullet. 

CLASS  I.  GREGARINID^E.** 
CLASS  II.  RHIZOPODA. 

Order  i.  Monera.** 

ii       2.  Amcebea.** 

ii       3.  Foraminifera. 

ii       4.  Radiolaria  (Polycystines,  &c.) 

.,       5.   Spongida  (Sponges). 
CLASS  III.  INFUSORIA.** 

SUB-KINGDOM  II.— CCELENTERATA. 

Animal  simple  or  compound  ;  body-wall  composed  of  two  principal 
layers  ;  digestive  canal  freely  communicating  with  the  general  cavity  of  the 
body  ;  no  circulating  organs,  and  no  nervous  system  or  a  rudimentary  one  ; 
mouth  surrounded  by  tentacles,  arranged,  like  the  internal  organs,  in  a 
"  radiate  "  or  star-like  manner. 

CLASS  I.  HYDROZOA. 

Sub-class    I.    Hydroida    ("  Hydroid    Zoophytes").     Ex.    Presh- 

water    Polypes,**    Pipe  -  corallines     (Tubularia)t    Sea  -  Firs 

(Sertularia). 
Sub-class   2.    Siphonophora**    ("Oceanic    Hydrozoa").      Ex. 

Portuguese  Man-of-war  (Physalia). 


376        '  APPENDIX. 

Sub-class  3.   Discophora  ("Jelly-fishes  '').      Only  known  as  fossils 
by  impressions  of  their  stranded  carcasses. 

Sub-class  4.   Lucernarida  ("Sea-blubbers").      Also  only  known 
as  fossils  by  impressions  left  in  fine-grained  strata. 

Sub-class  5.    GraplolitidfZ*  ("  Graptolite^.  "). 
CLASS  II.  ACTINOZOA. 

Order  i.  Zoantharia.      Ex.    Sea-anemones**   (Actinidcz},    Star- 
corals  (Astneida;}. 

Order  2.  Alcyonaria.      Ex.    Sea-pens    (Pennatula\    Organ-pipe 
Coral  \Tubipora}%  Red  Coral  (Corallium). 

Order  3.   Riigosa  ("  Rugose  Corals"). 

ii       4.    Ctenophora.**     Ex.   Venus's  Girdle  {Cesium}. 

SUB- KING  DOM  III.— ANNULOIDA. 

Animals  in  which  the  digestive  canal  is  completely  shut  off  from  the 
cavity  of  the  body  ;  a  distinct  nervous  system  ;  a  system  of  branched 
"  water- vessels,"  which  usually  communicate  with  the  exterior.  Body  of 
the  adult  often  "radiate,"  and  never  composed  of  a  succession  of  definite 
rings. 

CLASS    I.    ECHINODERMATA. 

Order  i.    Crinoidea  ("Sea-lilies").      Ex.    Feather  star     Coma- 
tula),  Stone-lily  (Encrinus*). 
Order  2.  Blastoidea*  ("  Pentremites  "). 

„       3.   Cystoidea*  ("Globe-lilies"). 

it       4.   Ophiuroidea  ("  Brittle-stars").     Ex.   Sand-stars  (Ophi- 

ura\   Brittle-stars  (Ophiocoma). 
Order  5.  Asteroidea  ("Star-fishes").      Ex.   Cross-fish  (Uraster), 

Sun-star  (Solasftr). 
Order  6.  Echinoidea  ("Sea-urchins").     Ex.  Sea-eggs  (Echinus'], 

Heart-urchins  (Spatang/is). 
Order  7.   Holothuroidea    ("  Sea- cucumbers  ").      Ex.     Trepangs 

(Holothuria). 
CLASS  II.   SCOLECIDA  **  (Intestinal  Worms,  Wheel  Animalcules,  &c.) 

SUB-KINGDOM  IV. — ANNULOSA. 

Animal  composed  of  numerous  definite  segments  placed  one  behind  the 
other  ;  nervous  system  forming  a  knotted  cord  placed  along  the  lower 
(ventral)  surface  of  the  body. 

Division  A.  Anarthropoda.     No  jointed  limbs. 

CLASS  I.   GEPHYREA  **("  Spoon-worms"). 

CLASS  II.  ANNELIDA  ("Ringed-worms"').     Ex.  Leeches**  (Hirudinca), 

Earthworms**  (Oligochccta\  Tube-worms  (7'tibicola),   Sea -worms 

and  Sea-centipedes  (Errantia). 
CLASS  III.  CH^ETOGNATHA**  ("Arrow- worms  "). 

Division  B.  Arthropoda  or  Articulata.     Limbs  jointed  to  the  body. 

CLASS  I.  CRUSTACEA  ("  Crustaceans ").  Ex.  Barnacles  and  Acorn- 
shells  ( Cirripedia) ,  Water -fleas  (Ostracoda),  Brine -shrimps  and 
Fairy-shrimps  (Phyllopodd),  Trilobites  *  (Trilobitd),  King-crabs 
and  Eurypterids  *  (Merostomata),  Wood-lice  and  Slaters  (Isopoda), 
Sand-hoppers  (Amphipoda],  Lobsters,  Shrimps,  Hermit-crabs,  and 
Crabs  (Decapodn}. 


APPENDIX.  377 

CLASS  II.  ARACHNIDA.  Ex.  Mites  (Acarina],  Scorpions  (Pedipalpi], 
Spiders  (Araneida). 

CLASS  III.  MYRIAPODA.  Ex.  Centipedes  (Chilopoda),  Millipedes  and 
Galley-worms  (Chilognatha). 

CLASS  IV.  INSECTA  ("Insects").  Ex.  Field-bugs  (Hemiptera]  ;  Crick- 
ets, Grasshoppers,  &c.  (Orthoptera)  ;  Dragon-flies  and  May-flies 
(Neuroptera]  ;  Gnats  and  House-flies  (Diptera)  ;  Butterflies  and 
Moths  (Lepidoptera]  ;  Bees,  Wasps,  and  Ants  (Hymenoplera]  ; 
Beetles  (Coleoptera). 

SUB-KINGDOM  V. — MOLLUSCA. 

Animal  soft-bodied,  generally  with  a  hard  covering  or  shell ;  no  dis- 
tinct segmentation  of  the  body ;  nervous  system  of  scattered  masses. 
CLASS  I.    POLYZOA   ("Sea-Mosses").     Ex.   Sea-mats    (Flustra),    Lace- 
corals  (Fenestellidiz*). 

CLASS  II.  TUNICATA**  ("  Tunicaries").     Ex.   Sea-squirts  (Ascidia}. 
CLASS   III.    BRACHIOPODA   (''Lamp-shells').      Ex.  Goose-bill   Lamp- 

shell  (Lingula). 
CLASS  IV.  LAMELLIBRANCHIATA  ("Bivalves").     Ex.   Oyster  (Ostrea], 

Mussel  (Mytilus],   Scallop  (Pecten],   Cockle  (Cardiuin). 
CLASS  V.    GASTEROPODA   ("Univalves").      Ex.    Whelks   (Buccimim), 

Limpets  (Patella],   Sea-slugs**  (Doris],   Land-snails  (Helix). 
CLASS  VI.  PTEROPODA  ("Winged  Snails'").     Ex.  Hyalea,  Cleodora. 
CLASS  VII.  CEPHALOPODA  ("Cuttle-fishes").     Ex.   Calamary  (Loligo], 
Poulpe    (Octopus),    Paper   Nautilus    (Argonattta],   Pearly  Nautilus 
(Nautilus],  Belemnites,*  Orthoceratites,*  Ammonites.* 


VERTEBRATE  ANIMALS. 

SUB-KINGDOM  VI. — VERTEBRATA. 

Body  composed  of  definite  segments  arranged  longitudinally  one  behind 
the  other ;  main  masses  of  the  nervous  system  placed  dorsally ;  a  back- 
bone or  "vertebral  column  "  in  the  majority. 

CLASS  I.  PISCES  ("  Pishes").  Ex.  Lancelet**  (Amphioxns)  ;  Lampreys 
and  Hag-fishes  (Marsipobranchii'**}',  Herring,  Salmon,  Perch,  &c. 
(Teleostei  or  "  Bony  Fishes  ");  Gar-pike,  Sturgeon,  &c.  (Ganoidei]; 
Sharks,  Dog-fishes,  Rays,  &c.  (Elasmobranchii  or  "  Placoids"). 
CLASS  II.  AMPHIBIA  ("Amphibians").  Ex.  Labyrinth odoniia,*  Cge- 
cilians,  **  Newts  and  Salamanders  (Urodela),  Frogs  and  Toads 
(Anoura). 

CLASS  III.  REPTILTA  ("Reptiles").  Ex.  Deinosauria,*  Pterosauria,* 
Anomodontia*  Plesiosaurs  (Sauropterygia*},  Ichthyosaurs  (Ichlhy- 
opterygia*],  Tortoises  and  Turtles  (Chelonia],  Snakes  (Ophidia), 
Lizards  (Lacertilia],  Crocodiles  (Crocodilia]. 

CLASS  IV.  AVES  ("Birds").  Ex.  Toothed  Birds  (Odontornithes*]  ; 
Lizard-tailed  Birds  (Archaopteryx  *)  ;  Ducks,  Geese,  Gulls,  &c. 
(Natatores]  ;  Storks,  Herons,  Snipes,  Plovers,  &c.  ( Grallatores] ; 
Ostrich,  Emeu,  Cassowary,  Dinornis,*  ^piornis,*  &c.  (Cursores)  ; 
Fowls,  Game  Birds,  and  Doves  (Rasores] ;  Cuckoos,  Woodpecker?, 
Parrots,  &c.  (Scansores]  ;  Crows,  Starlings,  Finches,  Humming- 
birds, Swallows,  &c.  (Insessores}  ;  Owls,  Hawks,  Eagles,  Vultures 
(Kaf  tores). 


378  APPENDIX. 

CLASS  V.  MAMMALIA  ("Quadrupeds").  Ex.  Duck-mole  and  Spiny 
Ant-eater  (Monotremata**)  ;  Kangaroos,  Phalangers,  Opossums, 
Tasmanian  Devil,  &c.  (Marsupialia)  ;  Sloths,  Ant-eaters,  Arma- 
dillos (Edentata}  ;  Manatees  and  Dugongs  (Sircnia]  ;  Whales, 
Dolphins,  Porpoises  (Cetacea}  ;  Rhinoceros,  Tapir,  Horses,  Hip- 
popotamus, Pigs,  Camels  and  Llamas,  Giraffes,  Deer,  Antelopes, 
Sheep,  Goats,  Oxen  (Ungitlata]  ;  Hyrax  (Hyracoidta**')',  Ele- 
phants, Mastodon,*  Deinotherium*  (Proboscidca}  ;  Seals,  Walrus, 
Bears,  Dogs,  Wolves,  Cats,  Lions,  Tigers,  &c.  (Carnivora)  ; 
Hares,  Rabbits,  Porcupines,  Beavers,  Rats.  Mice,  Lemmings, 
Squirrels,  Marmots,  &c.  (Rodentici)  ;  Bats  (Cheiroptera]  ;  Moles, 
Shrew-mice,  Hedgehogs  (Insectivora)  ;  Lemurs,  Spider-monVeys, 
Macaques,  Baboons,  Apes  (Qua  drum  a  11  a] ;  Man  (Bimana). 


GLOSSARY. 


ABDOMEN  (Lat.  abdo,  I  conceal).  The  posterior  cavity  of  the  body,  contain- 
ing the  intestines  and  others  of  the  viscera.  In  many  Invertebrates  there 
is  no  separation  of  the  body-cavity  into  thorax  and  abdomen,  and  it  is  only 
in  the  higher  Annulosa  that  a  distinct  abdomen  can  be  said  to  exist. 

ABERRANT  (Lat.  aberro,  I  wander  away).     Departing  from  the  regular  type. 

ABNORMAL  (Lat.  ab,  from ;  norma,  a  rule).  Irregular ;  deviating  from  the 
ordinary  standard. 

ACRODUS  (Gr.  akros,  high  ;  odous,  tooth).  A  genus  of  the  Cestraciont  fishes, 
so  called  from  the  elevated  teeth. 

ACROGENS  (Gr.  akros,  high  ;  gennao,  I  produce).  Plants  which  increase  in 
height  by  additions  made  to  the  summit  of  the  stem  by  the  union  of  the 
bases  of  the  leaves. 

ACROTRETA  (Gr.  akros,  high ;  tretos,  pierced).  A  genus  of  Brachiopods,  so 
called  from  the  presence  of  a  foramen  at  the  summit  of  the  shell. 

ACTINOCRINUS  (Gr.  aktin,  a  ray ;  krinon,  a  lily).     A  genus  of  Crinoids. 

ACTINOZOA  (Gr.  aktin,  a  ray  ;  and  zoon,  an  animal).  That  division  of  the 
Coelenterata  of  which  the  Sea-anemones  may  be  taken  as  the  type. 

MOLINA  (JEgU,  a  sea-nymph).     A  genus  of  Trilobites. 

^EPIORNIS  (Gr.  aipus,  huge ;  ornis,  bird).  A  genus  of  gigantic  Cursorial 
birds. 

AGNOSTUS  (Gr.  a,  not ;  gignosko,  I  know).     A  genus  of  Trilobites. 

ALCES  (Lat.  alces,  elk).     The  European  Elk  or  Moose. 

ALECTO  (the  proper  name  of  one  of  the  Furies).     A  genus  of  Polyzoa. 

ALETHOPTERIS  (Gr.  alelhes,  true  ;  pteris,  fern).     A  genus  of  Ferns. 

ALG^E  (Lat.  alga,  a  marine  plant).  The  order  of  plants  comprising  the  Sea- 
weeds and  many  fresh-water  plants. 

ALVEOLUS  (Lat.  alvus,  belly).     Applied  to  the  sockets  of  the  teeth. 

AMBLYPTERUS  (Gr.  amblus,  blunt ;  pteron,  fin).     An  order  of  Ganoid  Fishes. 

AMBONYCHIA  (Gr.  ambon,  a  boss ;  onux,  claw).  A  genus  of  Palaeozoic  Bi- 
valves. 

AMBULACRA  (Lat.  antbulacrum,  a  place  for  walking).  The  perforated  spaces 
or  "  avenues  "  through  which  are  protruded  the  tube-feet,  by  means  of  which 
locomotion  is  effected  in  the  Echinodermata. 

AMMONITID.E.  A  family  of  Tetrabranchiate  Cephalopods,  so  called  from  the 
resemblance  of  the  shell  of  the  type-genus,  Ammonites,  to  the  horns  of  the 
Egyptian  God,  Jupiter- Ammon. 

AMORPHOZOA  (Gr.  a,  without ;  morphe,  shape  ;  zotin,  animal).  A  name  some- 
times used  to  designate  the  Sponges. 

AMPHIBIA  (Gr.  amphi,  both  ;  bios,  life).  The  Frogs,  Newts,  and  the  like, 
which  have  gills  when  young,  but  can  always  breathe  air  directly  when 
adult. 

AMPHICYON  (Gr.  amphi,  both— implying  doubt;  kuSn,  dog).  An  extinct 
genus  of  Camivora. 


3^0  CxLOSSARV. 

AMPHILESTES  (Gr.  amphi,  both;  lestes,  a  thief).     A  genus  of  Jurassic  Mam- 
mals. 
AMPHISPONGIA  (Gr.  amphi,  both ;   spoggos,  sponge).     A  genus  of  Silurian 

sponges. 

AMPHISTEGINA  (Gr.  amphi,  both  ;  stepe,  roof).     A  genus  of  Foraminifera. 
AMPHITHERIUM  (Gr.  amphi,  both  ;  th'-rion,  beast).    A  genus  of  Jurassic  Mam- 
mals. 
AMPHITRAGULUS  (Gr.  amphi,  both  ;  dim.  of  tragos,  goat).     An  extinct  genus 

related  to  the  living  Musk-deer. 

AMPLEXUS  (Lat.  an  embrace).     A  genus  of  Rugose  Corals. 
AMPYX  (Gr.  ampux,  a  wreath  or  wheel).     A  genus  of  Trilobites. 
ANARTHROPODA  (Gr.  a.  without ;  arthros,  a  joint ;  pous,  foot).     That  division 

of  Annulose  animals  in  which  there  are  no  articulated  appendages. 
ANCHITHERIDM  (Gr.  agchi,  near  ;  therion,  beast).   An  extinct  genus  of  Mammals. 
ANCYLOCERAS  (Gr.  agkulos,  crooked  ;  ceras,  horn).     A  genus  of  Ammonitidie. 
ANCYLOTHERIUM  (Gr.  agkulos,  crooked  ;  therion,  beast).     An  extinct  genus  of 

Edentate  Mammals. 

ANDRIAS  (Gr.  andrias,  image  of  man).     An  extinct  genus  of  tailed  Amphi- 
bians. 
ANGIOSPERMS  (Gr.  anyeion,  a  vessel ;  sperma,  seed).     Plants  which  have  their 

seeds  enclosed  in  a  seed-vessel. 
ANNELIDA  (a  Gallicised  form  of  Annulata).     The  Ringed  Worms,  which  form 

one  of  the  divisions  of  the  A  narthropoda. 
ANNULARIA  (Lat.  annulus,  a  ring).    A  genus  of  Palaeozoic  plants,  with  leaves 

in  whorls. 
ANNULOSA  (Lat.  annulus).     The  sub-kingdom  comprising  the  Anarthropoda 

and  the  Arthropoda  or  Articulata,  in  all  of  which  the  body  is  more  or  less 

evidently  composed  of  a  succession  of  rings. 
ANOMODONTIA  (Gr.  anomos,  irregular;    odous,  tooth).     An  extinct  order  of 

Reptiles,  often  called  Dicynodontia. 
ANOMURA  (Gr.  anomos,  irregular  ;  oura,  tail).    A  tribe  of  Decapod  Crustacea, 

of  which  the  Hermit-crab  is  the  type. 
ANOPLOTHERHLE  (Gr.  anoplos,  imarmed ;  thtr,  beast).     A  family  of  Tertiary 

Ungulates. 
ANOURA  (Gr.  a,  without ;  oura,  tail).     The  order  of  Amphibia  comprising  the 

Frogs  and  Toads,  in  which  the  adult  is  destitute  of  a  tail.     Often  -called 

Batrachia. 
ANTENNA  (Lat.  antenna,  a  yard-arm).    The  jointed  horns  or  feelers  possessed 

by  the  majority  of  the  Articulata. 
ANTENNULES  (dim.  of  Antennae).     Applied  to  the  smaller  pair  of  antennae  in 

the  Crustacea. 
ANTHRACOSAURUS  (Gr.  anthrax,  coal ;  saura,  lizard).    A  genus  of  Labyrintho- 

dont  Amphibians. 
ANTHRAPAL^MON  (Gr.  anthrax,  coal ;  palcemon,  a  prawn — originally  a  proper 

name).     A  genus  of  long-tailed  Crustaceans  from  the  Coal-measures. 
ANTLERS.     Properly  the  branches  of  the  horns  of  the  Deer  tribe  (Cervidce),  but 

generally  applied  to  the  entire  horns. 
APIOCRINID.E  (Gr.  apion,  a  pear ;  krinon,  lily).     A  family  of  Crinoids — the 

' '  Pear-encrinites." 
APTERYX  (Gr.  a,  without ;  pterux,  a  wing).     A  wingless  bird  of  New  Zealand, 

belonging  to  the  order  Cursores. 

AQUEOUS  (Lat.  aqua,  water).     Formed  in  or  by  water. 
ARACHNIDA  (Gr.  arachne,  a  spider).     A  class  of  the  Articulata,  comprising 

Spiders,  Scorpions,  and  allied  animals. 
ARBORESCENT.     Branched  like  a  tree. 

ARCHLEOCIDARIS  (Gr.  archaios,  ancient ;  Lat.  cidaris,  a  diadem).     A  Paleo- 
zoic genus  of  Sea-urchins,  related  to  the  existing  Cidaris. 
AKCHLEOCYATHUS  (Gr.  archaiog,  ancient ;  kuathos,  cup).    A  genus  of  Palaeozoic 

fossils  allied  to  the  Sponges. 
ARCH^EOPTERYX  (Gr.  archaios,  ancient ;  ptfrux,  a  wing).     The  singular  fossil 

bird  which  alone  constitutes  the  order  of  the  taururce. 


GLOSSARY.  38! 

ARCTOCYOX  (Gr.  arctos,  beat  ;  ktion,  dog).     An  extinct  genus  of  Carnivora. 

ARENACEOUS.     Sandy,  or  composed  of  grains  of  sand. 

ARENICOLITES  (Lat.  arena,  sand  ;  colo,  I  inhabit).  A  genus  founded  on  bur- 
rows supposed  to  be  formed  by  worms  resembling  the  living  Lobworms 
(Arenicola). 

ARTICDLATA  (Lat.  articulns,  a  joint).  A  division  of  the  animal  kingdom,  com- 
prising Insects,  Centipedes,  Spiders,  and  Crustaceans,  characterised  by  the 
possession  of  jointed  bodies  or  jointed  limbs.  The  term  Arthropoda  is  now 
more  usually  employed. 

ARTIODACTYLA  (Gr.  artios,  even  ;  daktulos,  a  finger  or  toe).     A  division  of 
hoofed  quadrupeds  ( Uiujulata)  in  which  each  foot  has  an  even  number 
toes  (two  or  four). 

ASAPHUS  (Gr.  asaphes,  obscure).     A  genus  of  Trilobites. 

ASCOCERAS  (Gr.  askos,  a  leather  bottle  ;  keras,  horn).  A  genus  of  Tetrabran- 
chiate  Cephalopods. 

ASIPHONATE.  Not  possessing  a  respiratory  tube  or  siphon.  (Applied  to  a 
division  of  the  Lamellibrancldate  Molluscs.) 

ASTEROID  (Gr.  aster,  a  star;  and  eidos,  form).  Star-shaped,  or  possessing 
radiating  lobes  or  rays  like  a  star-fish. 

ASTEROIDEA.  An  order  of  Kchinudermata,  comprising  the  Star-fishes,  charac- 
terised by  their  rayed  form. 

ASTEROPHYLLITES  (Gr.  aster,  a  star ;  phullon,  leaf).  A  genus  of  Palaeozoic 
plants,  with  leaves  in  whorls. 

AsTRjEiDjE  (Gr.  Astrcea,  a  proper  name).     The  family  of  the  Star-corals. 

ASTYLOSPONGIA  (Gr.  a,  without;  stulos,  a  column ;  spoggos,  a  sponge).  A 
genus  of  Silurian  Sponges. 

ATHYRIS  (Gr.  a,  without ;  thura,  door).     A  genus  of  Brachiopods. 

ATRYPA  (Gr.  a,  without ;  trupa,  a  hole).     A  genus  of  Brachiopods. 

AVES  (Lat.  avis,  a  bird).     The  class  of  the  Birds. 

AVICULA  (Lat.  a  little  bird).  The  genus  of  Bivalve  Molluscs  comprising  the 
Pearl-oysters. 

AXOPHYLLUM  (Gr.  axon,  a  pivot;  phullon,  a  leaf).  A  genus  of  Rugose 
Corals. 

Azoic  (Gr.  a,  without ;  zoe,  life).     Destitute  of  traces  of  living  beings. 

BACULITES  (Lat.  baculum,  a  staff).     A  genus  of  the  Ammo  nit  idee. 

BAL2ENA  (Lat.  a  whale).     The  genus  of  the  Whalebone  Whales. 

BALANID.E  (Gr.  lalanos,  an  acorn).  A  family  of  sessile  Cirripedes,  commonly 
called  "  Acorn-shells." 

BATRACHIA  (Gr.  latrachos,  a  frog).  Often  loosely  applied  to  any  of  the  Am- 
phibia, but  sometimes  restricted  to  the  Amphibians  as  a  class,  or  to  the 
single  order  of  the  Anoura. 

BELEiMNiTiD^E  (Gr.  bdemnon,  a  dart).  An  extinct  group  of  Dibranchiate  Ceph- 
alopods, comprising  the  Belemnites  and  their  allies. 

BELEMNOTEUTHIS  (Gr.  belemnon,  a  dart ;  teuthis,  a  cuttle-fish).  A  germs  allied 
to  the  Belemnites  proper. 

BELINURUS  (Gr.  belos,  a  dart ;  oura,  tail).     A  genus  of  fossil  King-crabs. 

BELLEUOPHON  (Gr.  proper  name).     A  genus  of  oceanic  Univalves  (Heteropoda). 

BKLOTEUTHIS  (Gr.  belos,  a  dart  ;  teuthis,  a  cuttle-fish).  An  extinct  genus  of 
Dibranchiate  Cephalopods. 

BEYRICHIA  (named  after  Prof.  Beyrich).     A  genus  of  Ostracode  Crustaceans. 

BILATERAL.     Having  two  symmetrical  sides. 

BIMANA  (Lat.  bis,  twice ;  manus,  a  hand).  The  order  of  Mammalia  compris- 
ing man  alone. 

BIPEDAL  (Lat.  bis,  twice ;  pes,  foot).     Walking  upon  two  legs. 

BIVALVE  (Lat.  bis,  twice  ;  valvce,  folding-doors).  Composed  of  two  plates  or 
valves  ;  applied  to  the  shell  of  the  Lamellibranchiata  and  Brachiopoda,  and 
to  the  carapace  of  certain  Crustacea. 

BLASTOIDEA  (Gr.  blastos,  a  bud  ;  and  eidos,  form).  An  extinct  order  of  Ecld- 
nodermata,  often  called  Pentremites.  • 

BRACHIOPODA  (Gr.  brachion,  an  arm  ;  ponx,  the  foot).     A  class  of  the  Mollits- 


382  GLOSSARY. 

coida,  often  called  "Lamp-shells,"  characterised  by  possessing  tv/o  fleshy 
arms  continued  from  the  sides  of  the  mouth. 

BRACHYURA  (Gr.  brachus,  short ;  aura,  tail).  A  tribe  of  the  Decapod  Crusta- 
ceans with  short  tails  (i.e.,  the  Crabs). 

BRADYPODID.E  (Gr.  bradus,  slow ;  podes,  feet).  The  family  of  Edentata  com- 
prising the  Sloths. 

BRANCHIA  (Gr.  bragchia,  the  gill  of  a  fish).  A  respiratory  organ  adapted  to 
breathe  air  dissolved  in  water. 

BRANCHIATE.     Possessing  gills  or  branchiae. 

BRONTEUS  (Gr.  bronte,  thunder— an  epithet  of  Jupiter  the  Thunderer).  A 
genus  of  Trilobites. 

BRONTOTHERIUM  (Gr.  bronte,  thunder  ;  thsrion  beast).  An  extinct  genus  of 
Ungulate  Quadrupeds. 

BRONTOZOUM  (Gr.  bronte,  thunder  ;  zoon,  animal).  A  genus  founded  on  the 
largest  footprints  of  the  Triassic  Sandstones  of  Connecticut. 

BUCCINUM  (Lat.  biicc&iium,  a  trumpet).  The  genus  of  Univalves  comprising 
the  Whelks. 

CAINOZOIC    (See  Kainozoic. ) 

CALAMITES  (Lat.  calamus,  a  reed).  Extinct  plants  with  reed-like  stems,  be- 
lieved to  be  gigantic  representatives  of  the  Eqnisetacece. 

CALCAREOUS  (Lat.  calx,  lime).     Composed  of  carbonate  of  lime. 

CALICE.  The  little  cup  in  which  the  polype  of  a  coralligenous  Zoophyte  (Ac- 
tinozoon)  is  contained. 

CALYMENK  (Gr.  kabtmM,  concealer!).     A  genus  of  Trilobites. 

CALYX  (Lat.  a  cup).  Applied  to  the  cup-shaped  body  of  a  Crinoid  (Echino- 
dermata). 

CAMAROPHORIA  (Gr.  kamara,  a  chamber ;  phero,  I  carry).  A  genus  of  Brachio- 
pods. 

CAMELOPARDALID.E  (Lat.  camelus,  a  camel ;  pardalis,  a  panther).  The  family 
of  the  Giraffes. 

CANINE  (Lat.  cants,  a  dog).  The  eye-tooth  of  Mammals,  or  the  tooth  which 
is  placed  at  or  close  to  the  prsemaxillary  suture  in  the  upper  jaw,  and  the 
corresponding  tooth  in  the  lower  jaw. 

CARAPACE.  A  protective  shield.  Applied  to  the  upper  shell  of  Crabs,  Lobsters, 
and  many  other  Crustacea.  Also  the  upper  half  of  the  immovable  case  in 
which  the  body  of  a  Chelonian  is  protected. 

CARCHARODON  (Gr.  karcharos.  rough  ;  odous,  tooth).     A  genus  of  Sharks. 

CARDIOCARPON  (Gr.  kardia,  the  heart ;  karpos,  fruit).  A  genus  of  fossil  fruit 
from  the  Coal-measures. 

CARDIUM  (Gr.  kardia,  the  heart).  The  genus  of  Bivalve  Molluscs  comprising 
the  Cockles.  Cardinia,  Cardiola,  and  Cardita  have  the  same  derivation. 

CARNIVORA  (Lat.  caro,  flesh ;  voro,  I  devour).  An  order  of  the  Mammalia. 
The  "Beasts  of  Prey." 

CARNIVOROUS  (Lat.  caro,  flesh  ;  vcro,  I  devour).     Feeding  upon  flesh. 

CARYOCARIS  (Gr.  karua,  a  nut ;  karis,  a  shrimp).  A  genus  of  Phyllopod  Crus- 
taceans. 

CARYOCRINUS  (Gr.  karua,  a  nut ;  krinon,  a  lily).     A  genus  of  Cystideans. 

CAUDAL  (Lat.  cauda,  the  tail).     Belonging  to  the  tail. 

CAVICORNIA  (Lat.  cavus,  hollow;  cornu,  a  horn).  The  '-'hollow-horned" 
Euminants,  in  which  the  horn  consists  of  a  central  bony  "horn-core  "  sur- 
rounded by  a  horny  sheath. 

CENTRUM  (Gr.  kentron,  the  point  round  which  a  circle  is  described  by  a  pair 
of  compasses).  The  central  portion  or  "body"  of  a  vertebra. 

CEPHALASPID.E  (Gr.  kephale,  head ;  aspis,  shield).     A  family  of  fossil  fishes. 

CEPHALIC  (Gr.  kephale,  head).     Belonging  to  the  head. 

CEPHALOPODA  (Gr.  kephale  ;  and  podes,  feet).  A  class  of  the  Mollusca,  com- 
prising the  Cuttle-fishes  and  their  allies,  in  which  there  is  a  series  of  arms 
ranged  round  the  head. 

CERATIOCARIS  (Gr.  kcras,  a  horn ;  karis,  a  shrimp).  A  genus  of  Phyllopod 
Crustaceans. 


GLOSSARY.  383 

CERATITES  (Gr.  keras,  a  horn).     A  genus  of  Ammonitidce. 

CERATODUS  (Gr.  keras,  a  horn  ;  odous,  tooth).     A  genus  of  Dipnoous  fishes. 

CERVICAL  (Lat.  cervix,  the  neck).  Connected  with  or  belonging  to  the  region 
of  the  neck. 

CERVID^  (Lat.  cervus,  a  stag).     The  family  of  the  Deer. 

CESTRAPHORI  (Gr.  kestra,  a  weapon  ;  phero,  I  carry).  The  group  of  the  "Ces- 
traciont  Fishes,"  represented  at  the  present  day  by  the  Port-Jackson  Shark  ; 
so  called  from  their  defensive  spines. 

CETACEA  (Gr.  ketos,  a  whale).  The  order  of  Mammals  comprising  the  Whales 
and  the  Dolphins. 

CETIOSAURUS  (Gr.  ketos,  whale  ;  saura,  lizard).  A  genus  of  Deinosaurian 
Reptiles. 

CHEIROPTERA  (Gr.  clteir,  hand ;  pteron,  wing).  The  Mammalian  order  of  the 
Bats. 

CHEIROTHERIUM  (Gr.  cheir,  hand  ;  tkerion,  beast).  The  generic  name  applied 
originally  to  the  hand-shaped  footprints  of  Labyrinthodonts. 

CHEIRURUS  (Gr.  cheir,  hand  ;  oura,  tail).     A  genus  of  Trilobites. 

CHELONIA  (Gr.  chelone,  a  tortoise).  The  Reptilian  order  of  the  Tortoises  and 
Turtles. 

CHONETES.  (Gr.  chone  or  choane,  a  chamber  or  box).     A  genus  of  Brachiopods. 

CIDARIS  (Lat.  a  diadem).     A  genus  of  Sea-urchins. 

CLADODUS  (Gr.  klados,  branch  ;  odous,  tooth).     A  genus  of  Fishes. 

CLATHROPORA  (Lat.  clathri,  a  trellis  ;  poms,  a  pore).  A  genus  of  Lace-corals 
(Polyzoa). 

CLISIOPHYLLUM  (Gr.  klision,  a  hut ;  phullon,  leaf).    A  genus  of  Rugose  Corals. 

CLYMENIA  (Clumene,  a  proper  name).    A  genus  of  Tetrabranchiate  Cephalopods. 

COCCOSTEUS  (Gr.  kokkos,  berry  ;  osteon,  bone).     A  genus  of  Ganoid  Fishes. 

COCHLIODUS  (Gr.  kochlion,  a  snail-shell ;  odous,  tooth).  A  genus  of  Cestra- 
ciont  Fishes. 

C(ELENTERATA  (Gr.  koilos,  hollow  ;  enteron,  the  bowel).  The  sub-kingdom 
which  comprises  the  Hydrozoa  and  Actinozoa.  Proposed  by  Frey  and 
Leuckhart  in  place  of  the  old  term  Radiata,  which  included  other  animals 
as  well. 

COLEOPTERA  (Gr.  koleos,  a  sheath  ;  pteron,  wing).  The  order  of  Insects 
(Beetles)  in  which  the  anterior  pair  of  wings  are  hardened,  and  serve  as  pro- 
tective cases  for  the  posterior  pair  of  membranous  wings. 

COLOSSOCHELYS  (Gr.  kolossos,  a  gigantic  statue ;  chelus,  a  tortoise).  A  huge 
extinct  Land-tortoise. 

COMATULA  (Gr.  koma,  the  hair).  The  Feather-star,  so  called  in  allusion  to  its 
tress-like  arms. 

CONDYLE  (Gr.  kondulos,  a  knuckle).  The  surface  by  which  one  bone  articulates 
with  another.  Applied  especially  to  the  articular  surface  or  surfaces  by 
which  the  skull  articulates  with  the  vertebral  column. 

CONIFER^  (Lat.  conus,  a  cone ;  fero,  I  carry).  The  order  of  the  Firs,  Pines, 
and  their  allies,  in  which  the  fruit  is  generally  a  "  cone  "  or  "  fir-apple." 

CONULARIA  (Lat.  conulus,  a  little  cone).     An  extinct  genus  of  Pteropods. 

COPROLITES  (Gr.  kopros,  dung ;  lithos,  stone).  Properly  applied  to  the  fossil- 
ised excrements  of  animals  ;  but  often  employed  to  designate  phosphatic  con- 
cretions which  are  not  of  this  nature. 

CORALLITE.  The  corallum  secreted  by  an  Actinozoon  which  consists  of  a  single 
polype ;  or  the  portion  of  a  composite  corallum  which  belongs  to,  and  is 
secreted  by,  an  individual  polype. 

CORALLUM  (from  the  Latin  for  Red  Coral).  The  hard  structures  deposited  in, 
or  by,  the  tissues  of  an  Actinozoon — commonly  called  a  "  coral." 

CORIACEOUS  (Lat.  corium,  hide).     Leathery. 

CORYPHODON  (Gr.  korus,  helmet ;  odous,  tooth).  An  extinct  genus  of  Mam- 
mals, allied  to  the  Tapirs. 

CRANIUM  (Gr.  kranion,  the  skull).  The  bony  or  cartilaginous  case  in  which 
the  brain  is  contained, 

CRETACEOUS  (Lat.  creta,  chalk).  The  formation  which  in  Europe  contains 
white  chalk  as  one  of  its  most  conspicuous  members. 


384  GLOSSARY. 

CRINOIDEA  (Gr.  krinon,  a  lily  ;  eidos,  form).    An  order  of  Echinorter/nata, 

comprising  forms  which  are  usually  stalked,  and  sometimes  resemble  lilies 

in  shape. 

CRIOCERAS  (Gr.  krios,  a  ram ;  keras,  a  horn).     A  genus  of  Ammonitidce. 
CROCODILIA  (Gr.  krokodeilos,  a  crocodile).     An  order  of  Reptiles. 
CROSSOPTERYGID.S:  (Gr.  krossotos,  a  fringe  ;  pterux,  a  fin).     A  sub-order  of 

Ganoids  in  which  the  paired  fins  possess  a  central  lobe. 
CRUSTACEA  (Lat.  crusta,  a  crust).     A  class  of  Articulate  animals,  comprising 

Crabs,  Lobsters,  &c.,  characterised  by  the  possession  of  a  hard  shell  or 

crust,  which  they  cast  periodically. 
CRYPTOGAMS  (Gr.  kruptos,  concealed  ;  gamos,  marriage).     A  division  of  plants 

in  which  the  organs   of  reproduction  are  obscure  and  there  are  no  true 

flowers. 
CTENACANTHUS  (Gr.  kteis,  a  comb ;  akantha,  a  thorn).    A  genus  of  fossil  fishes, 

named  from  its  fin-spines. 
CTENOID  (Gr.  kteis,  a  comb ;  eidos,  form).     Applied  to  those  scales  of  fishes 

the  hinder  margins  of  which  are  fringed  with  spines  or  comb-like  projections. 
CURSORES  (Lat.  curro,  I  run).     An  order  of  Aves,  comprising  birds  destitute 

of  the  power  of  flight,  but  formed  for  running  vigorously  (e.g.,  the  Ostrich 

and  Emeu). 

CUSPIDATE.     Furnished  with  small  pointed  eminences  or  "  cusps." 
CYATHOCRINUS  (Gr.  kuafhos,  »  cup  ;  krinon,  a  lily).     A  genus  of  Crinoids. 
CYATHOPHYLLUM  (Gr.  Jcuathos,  a  cup  ;  phullon,  a  leaf).     A  genus  of  Rugose 

Corals. 
CYCLOID  (Gr.  kuklos,  a  circle  ;  eidos,  form).    Applied  to  those  scales  of  fishes 

which  have  a  regularly  circular  or  elliptical  outline  with  an  even  margin. 
CYCLOPHTHALMUS  (Gr.  kuklos,  a  circle  ;  ophthalmos,  eye).    A  genus  of  fossil 

Scorpions. 
CYCLOSTOMI  (Gr.  kuklos,  and  stoma,  mouth).     Sometimes  used  to  designate  the 

Hag-fishes  and  Lampreys,  forming  the  order  Morsipobranchii. 
CYPR.EA  (a  name  of  Venus).     The  genus  of  Univalve  Molluscs  comprising  the 

Cowries. 
CYRTOCERAS  (Gr.  kurtos,  crooked ;  keras,  horn).     A  genus  of  Tetrabranchiate 

Cephalopoda. 
CYSTIPHYLLUM  (Gr.  kustis,  a  bladder  ;  phullon,  a  leaf).     A  genus  of  Rugose 

Corals. 
CYSTOIDEA  (Gr.  kustis,  a  bladder;  eidos,  form).     The  " Globe-crinoids,"  an 

extinct  order  of  Echinodcrmata. 

DADOXYLON  (Gr.  dadion,  a  torch ;  xulon,  wood).  An  extinct  genus  of  Con- 
iferous trees. 

DECAPODA  (Gr.  deka,  ten  ;  podes,  feet).  The  division  of  Crustacea  which  have 
ten  feet ;  also  the  family  of  Cuttle-fishes,  in  which  there  are  ten  arms  or 
cephalic  processes. 

DECIDUOUS  (Lat.  decido,  I  fall  off).  Applied  to  parts  which  fall  off  or  are  shed 
during  the  life  of  the  animal. 

DEINOSAURIA  (Gr.  deinos,  terrible  ;  saura,  lizard).  An  extinct  order  of  Rep- 
tiles. 

DEINOTHERIUM  (Gr.  deinos,  terrible;  therion,  beast).  An  extinct  genus  of 
Proboscidean  Mammals. 

DENDROGRAPTUS  (Gr.  dendron,  tree  ;  graplio,  I  write).  A  genus  of  Grapto- 
lites. 

DESMIDI.E.  Minute  fresh- water  plants,  of  a  green  colour,  without  a  siliceous 
epidermis. 

DiATOMACEJ3  (Gr.  diatemno,  I  sever).  An  order  of  minute  plants  which  are 
provided  with  siliceous  envelopes. 

DIBRANCHIATA  <Gr.  dis,  twice  ;  bragchia,  gill).  The  order  of  Cephalopoda 
(comprising  the  Cuttle-fishes,  &c.)  in  which  only  two  gills  are  present. 

DICERAS  (Gr.  dis,  twice  ;  keras,  horn).     An  extinct  genus  of  Bivalve  Molluscs. 

DICTYONEMA  (Gr.  diktuon,  a  net ;  nema,  thread).  An  extinct  genus  of  Poly- 
zoa  (?). 


GLOSSARY.  385 

DICYNODONTIA  (Gr.  dis,  twice ;  kuon,  dog ;  odous,  tootli).     An  extinct  order  of 

Reptiles. 

DIDYMOGRAPTUS  (Gr.  didumos,  twin  ;  grapho,  I  write).   A  genus  of  Graptolites. 
DIMORPHODON  (Gr.  dis,  twice ;  morphe,  shape ;  odous,  tooth).     A  genus  of 

Pterosaurian  Reptiles. 

DINICHTHYS  (Gr.  deinos,  terrible  ;  ichthus,  fish).     An  extinct  genus  of  Fishes 
DINOCERAS  (Gr.  deinos,  terrible  ;  keras,  horn).    An  extinct  genus  of  Mammals. 
DINOPHIS  (Gr.  deinos,  terrible  ;  ophis,  snake).     An  extinct  genus  of  Snakes. 
DINORNIS  (Gr.  deinos,  terrible  ;  ornis,  bird).     An  extinct  genus  of  Birds. 
DIPLOGRAPTUS  (Gr.  diplos,  double  ;  grapho,  I  write).    A  genus  of  Graptolites. 
DIPNOI  (Gr.  dis,  twice ;  pnoe,  breath).     An  order  of  Fishes,  comprising  the 

Mud-fishes,  so  called  in  allusion  to  their  double  mode  of  respiration. 
DIPROTODON  (Gr.  dis,  twice  ;  protos,  first ;  odous,  tooth).    A  genus  of  extinct 

Marsupials. 
DIPTERA  (Gr.  dis,  twice ;  pteron,  wing).      An  order  of  Insects  characterised 

by  the  possession  of  two  wings. 
DISCOID  (Gr.  diskos,  a  quoit ;  eidos,  form).     Shaped  like  a  round  plate  or 

quoit. 

DOLOMITE  (named  after  M.  Dolomieu).     Magnesian  limestone. 
DORSAL  (Lat.  dorsum,  the  back).     Connected  with  or  placed  upon  the  back. 
DROMATHERIUM  (Gr.  dromaios,  nimble  ;  therion,  beast).     A  genus  of  Triassic 

Mammals. 
DRYOPITHECUS  (Gr.  drus,  an  oak ;  pithekos,  an  ape).     An  extinct  genus  of 

Monkeys. 

ECHINODERMATA  (Gr.  echinos ;  and  derma,  skin).  A  class  of  animals  com- 
prising the  Sea-urchins,  Star-fishes,  and  others,  most  of  which  have  spiny 
skins. 

ECHINOIDEA  (Gr.  echinos  ;  and  eidos,  form).  An  order  of  Echinodermata,  com- 
prising the  Sea-urchins. 

EDENTATA  (Lat.  e,  without ;  dens,  tooth).  An  order  of  Mammalia,  often  called 
Bruta. 

EDENTULOUS.  Toothless,  without  any  dental  apparatus.  Applied  to  the 
mouth  of  any  animal,  or  to  the  hinge  of  the  Bivalve  Molluscs. 

ELASMOBRANCHII  (Gr.  elasma,  a  plate ;  bragchia,  gill).  An  order  of  Fishes, 
including  the  Sharks  and  Rays. 

ENALIOSAURIA  (Gr.  enalios,  marine  ;  saura,  lizard).  Sometimes  employed  as 
a  common  term  to  designate  the  extinct  Reptilian  orders  of  the  Ichthyosauria 
and  Plesiosatiria. 

EOCENE  (Gr.  eos,  dawn  ;  kainos,  new  or  recent).  The  lowest  division  of  the 
Tertiary  rocks,  in  which  species  of  existing  shells  are  to  a  small  extent 
represented. 

EOPHYTON  (Gr.  eos,  dawn  ;  phuton,  a  plant).  A  genus  of  Cambrian  fossils, 
supposed  to  be  of  a  vegetable  nature. 

EOZOON  (Gr.  eos,  dawn ;  zoon,  animal).  A  genus  of  chambered  calcareous  or- 
ganisms found  in  the  Laurentian  and  Huronian  formations. 

EQUILATERAL  (Lat.  aquus,  equal ;  latus,  side).  Having  its  sides  equal.  Usu- 
ally applied  to  the  shells  of  the  Brachiopoda.  When  applied  to  the  spiral 
shells  of  the  Foraminifera,  it  means  that  all  the  convolutions  of  the  shell  lie 
in  the  same  plane. 

EQUISETACE^:  (Lat.  equus,  horse  ;  seta,  bristle).  A  group  of  Cryptogam ous 
plants,  commonly  known  as  "Horse-tails." 

EQUIVALVE  (Lat.  cequus,  equal ;  valvce,  folding-doors).  Applied  to  shells  which 
are  composed  of  two  equal  pieces  or  valves. 

ERRANTIA  (Lat.  erro,  I  wander).  An  order  of  Annelida,  often  called  Nereidea, 
distinguished  by  their  great  locomotive  powers. 

EUOMPHALUS  (Gr.  eu,  well ;  omphalos,  navel).  An  extinct  genus  of  Univalve 
Molluscs. 

EURYPTERIDA  (Gr.  eurus,  broad ;  pteron,  wing).  An  extinct  sub-order  of  Crus- 
tacea. 

EXOGYRA  (Gr.  exo,  outside  ;  guros,  circle).     An  extinct  genus  of  Oysters. 


386 


GLOSSARV. 


FAUNA  (Lat.  Fauni,  the  rural  deities  of  the  Romans).  The  general  assemblage 
of  the  animals  of  any  region  or  district. 

FAVOSITES  (Lat.  favus,  a  honeycomb).     A  genus  of  Tabulate  Corals. 

FENESTELLID.E  (Lat.  fenestella,  a  little  window).  The  "  Lace-corals,"  a  group 
of  Palaeozoic  Polyzoans. 

FILICES  (Lat.  jUix,  a  fern).  The  order  of  Cryptogamic  plants  comprising  the 
Ferns. 

FILIFORM  (Lat.  jilum,  a  thread  ;  forma,  shape).     Thread-shaped. 

FLORA  (Lat.  Flora,  the  goddess  of  flowers).  The  general  assemblage  of  the 
plants  of  any  region  or  district. 

FORAMINIFERA  (Lat.  foramen,  an  aperture  ;  fero,  I  carry).  An  order  of  Pro- 
tozoa, usually  characterised  by  the  possession  of  a  shell  perforated  by  numer- 
ous pseudopodial  apertures. 

FRUGIVOROUS  (tat.  frux,  fruit ;  roro,  I  devour).     Living  upon  fruits. 

FUCOIDS  (Lat.  fucus,  sea-weed  ;  Gr.  eidos,  likeness).  Fossils,  often  of  an 
obscure  nature,  believed  to  be  the  remains  of  sea-weeds. 

FUSULINA  (Lat.  fusu-s,  a  spindle).     An  extinct  genus  of  Foraminifera. 

GANOID  (Gr  ganos,  splendour,  brightness).  Applied  to  those  scales  or  plates 
which  are  composed  of  an  inferior  layer  of  true  bone  covered  by  a  superior 
layer  of  polished  enamel. 

GANOIDEI.    An  order  of  Fishes. 

GASTEROPODA  (Gr.  gaster,  stomach  ;  pous,  foot).  The  class  of  the  Mollusca 
comprising  the  ordinary  Univalves,  in  whicli  locomotion  is  usually  effected  by 
a  muscular  expansion  of  the  under  surface  of  the  body  (the  "foot "). 

GLOBIGERINA  (Lat.  globus,  a  globe ;  gero,  I  carry).     A  genus  of  Foraminifera. 

GLYPTODON  (Gr.  glupho,  I  engrave  ;  odovx,  tooth).  An  extinct  genus  of  Arma- 
dillos, so  named  in  allusion  to  the  fluted  teeth. 

GONIATITES  (Gr.  gonia,  angle).     A  genus  of  Tetrabranchiate  Cephalopods. 

GRALLATORES  (Lat.  grallce,  stilts).     The  order  of  the  long-legged  Wading  Birds. 

GRAPTOLITID.E  (Gr.  grapho,  I  write ;  lithos,  stone).  An  extinct  sub-class  of 
the  Hydrozoa. 

GYMNOSPERMS  (Gr.  gumnos,  naked  ;  sperma,  seed).  The  Conifers  and  Cycads, 
in  which  the  seed  is  not  protected  within  a  seed-vessel. 

HALITHERIUM  (Gr.  hals,  sea ;  t/ierion,  beast).     An  extinct  genus  of  Sea-cows 

(Sirenia}. 

HAMITES  (Lat.  hamus,  a  hook).     A  genus  of  the  Ammonitida*. 
HELIOPHYLLUM  (Gr.  helios,  the  sun;   phullon,   leaf).      A  genus  of  Rugose 

Corals. 
HELLADOTHERIUM  (Gr.  Hellas,  Greece ;  therion,  beast).    An  extinct  genus  of 

Ungulate  Mammals. 
HEMIPTERA  (Gr.  hemi  ;  and  pteron,  wing).     An  order  of  Insects  in  which  the 

anterior  wings  are  sometimes  "  hernelytra." 
HESPERORNIS  (Gr.  Hesperos,  the  evening  star;  ornis,  bird).     An  extinct  genus 

of  Birds. 
HETEROCERCAL  (Gr.  heteros,  diverse ;  kerkos,  tail).     Applied  to  the  tail  of 

Fishes  when  it  is  unsymmetrical,  or  composed  of  two  unequal  lobes. 
HETEROPODA  (Gr.  heteros,  diverse ;  podes,  feet).     An  aberrant  group  of  the 

Gasteropods,  in  which  the  foot  is  modified  so  as  to  form  a  swimming  organ. 
HIPPARION  (Gr.  hi2)parion,  a  little  horse).     An  extinct  genus  of  Mquidce. 
HIPPOPOTAMUS  (Gr.  hippos,  horse  ;  potamos,  river).     A  genus  of  Hoofed  Quad- 
rupeds— the  "  River-horses." 
HIPPURITID^E  (Gr.  hippos,  horse ;  oura,  tail).     An  extinct  family  of  Bivalve 

Molluscs. 
HOLOPTYCHIUS  (Gr.  holos,   whole;  ptuche,  wrinkle).      An   extinct  genus  of 

Ganoid  Fishes. 
HOLOSTOMATA  (Gr.  holos,  whole  ;  stoma,  mouth).    A  division  of  Gasteropodous 

Molluscs,  in  which  the  aperture  of  the  shell  is  rounded,  or  "  entire." 
HOLOTHUROIDEA  (Gr.  holothourion  ;  and  eidos,  form).    An  order  of  Echinoder- 

mata  comprising  the  Trepangs. 


GLOSSARY.  387 

HOMOCERCAL  (Gr.  homos,  same ;  kerkos,  tail).  Applied  to  the  tail  of  Fishes 
when  it  is  symmetrical,  or  composed  of  two  equal  lobes. 

HYBODONTS  (Gr.  hubos,  curved ;  odous,  tooth).  A  group  of  Fishes  of  which 
Hybodus  is  the  type-genus. 

HYDROIDA  (Gr.  hudra ;  and  eidos,  form).  The  sub-class  of  the  Hydrozva, 
which  comprises  the  animals  most  nearly  allied  to  the  Hydra. 

HYDROZOA  (Gr.  hudra  ;  and  zoon,  animal).  The  class  of  the  Ccdenterata  which 
comprises  animals  constructed  after  the  type  of  the  Hydra. 

HYMENOPTERA  (Gr.  humen,  a  membrane ;  pteron,  a  wing).  An  order  of  In- 
sects (comprising  Bees,  Ants,  &c.)  characterised  by  the  possession  of  four 
membranous  wings. 

ICHTHYODORULITE  (Gr.  ichthus,  fish  ;  dorus,  spear ;  lithos,  stone).     The  fossil 

tin-spine  of  Fishes. 

ICHTHYOPTERYGIA  (Gr.  ichthus  ;  pterux,  wing).     An  extinct  order  of  Reptiles. 
ICHTHYORNIS  (Gr.  ichthus,  fish ;  ornis,  bird).     An  extinct  genus  of  Birds. 
ICHTHYOSAURIA  (Gr.  ichthus ;  saura,  lizard).      Synonymous  with  Ichthyop- 

terygia. 
IGUANODON  (Iguana,  a  living  lizard  ;  Gr.  odous,  tooth).    A  genus  of  Deinosau- 

rian  Reptiles. 
INCISOR  (Lat.  incido,  I  cut).     The  cutting  teeth  fixed  in  the  intermaxillary 

bones  of  the  Mammalia,  and  the  corresponding  teeth  in  the  lower  jaw. 
INEQUILATERAL.     Having  the  two  sides  unequal,  as  in  the  case  of  the  shells  of 

the  ordinary  bivalves  (Lamellibranchiata).     When  applied  to  the  shells  of 

the  Foraminifera,  it  implies  that  the  convolutions  of  the  shell  do  not  lie  in 

the  same  plane,  but  are  obliquely  wound  round  an  axis. 
INEQUI VALVE.  Composed  of  two  unequal  pieces  or  valves. 
INOCERAMUS  (Gr.  is,  a  fibre  ;  keramos,  an  earthen  vessel).  An  extinct  genus  of 

Bivalve  Molluscs. 
INSECTA  (Lat.  inseco,  I  cut  into).     The  class  of  articulate  animals  commonly 

known  as  Insects. 

INSECTIVORA  (Lat.  insectum,  an  insect ;  voro,  I  devour).    An  order  of  Mammals. 
INSECTIVOROUS.     Living  upon  Insects. 
INSESSORES  (Lat.  insedeo,  I  sit  upon).     The  order  of  the  Perching  Birds,  often 

called  Passeres. 

INTERAMBULACRA.     The  rows  of  plates  in  an  Echinoid  which  are  not  per- 
forated for  the  emission  of  the  "  tube-feet." 
INTKRMAXILL.E  or  PR^IMAXILL^.     The  two  bones  which  are  situated  between 

the  two  superior  maxillae  in  Vertebrata.      In  man,  and  some  monkeys,  the 

praemaxillae  anchylose  with  the  maxillae,  so  as  to  be  irrecognisable  in  the 

adult. 
INVERTEBRATA  (Lat.  in,  without ;  vertebra,  a  bone  of  the  back).     Animals 

without  a  spinal  column  or  backbone. 
ISOPODA  (Gr.  isos,  equal ;  podes,  feet).     An  order  of  Crustacea  in  which  the 

feet  are  like  one  another  and  equal. 

KAINOZOIC  (Gr.  kainos,  recent ;  zoe,  life).  The  Tertiary  period  in  Geology 
comprising  those  formations  in  which  the  organic  remains  approximate 
more  or  less  closely  to  the  existing  fauna  and  flora. 

LABYRINTHODONTIA  (Gr.  lalurinthos,  a  labyrinth ;  odous,  tooth).  An  extinct 
order  of  Amphibia,  so  called  from  the  complex  microscopic  structure  of  the 
teeth. 

LACERTHJA  (Lat.  lacerta,  a  lizard).  An  order  of  Reptilia  comprising  the  Liz- 
ards and  Slow-worms. 

LAMELLIBRANCHIATA  (Lat.  lamella,  a  plate  ;  Gr.  bragchia,  gill).  The  class  of 
Mollusca  comprising  the  ordinary  bivalves,  characterised  by  the  possession 
of  lamellar  gills. 

LEPIDODENDRON  (Gr.  lepis,  a  scale  ;  dendron,  a  tree).  A  genus  of  extinct  plants, 
so  named  from  the  scale-like  scars  upon  the  stem  left  by  the  falling  off'  of  the 
leaves. 


388  GLOSSARY. 

LEPIDOPTERA  (Gr.  lepis,  a  scale ;  pteron,  a  wing).  An  order  of  Insects,  coir- 
prising  Butterflies  and  Moths,  characterised  by  possessing  four  wings  which 
are  usually  covered  with  minute  scales. 

LEPIDOSIREN  (Gr.  lepis,  a  scale  ;  seiren,  a  siren — the  generic  name  of  the  Mud- 
eel  or  Siren  lacertina).  A  genus  of  Dipnoous  fishes,  comprising  the  "  Mud- 
fishes." 

LEPIDOSTROBUS  (Gr.  lepis,  a  scale  ;  strobilos,  a  fir-cone).  A  genus  founded  on 
the  cones  of  Lepidodendron. 

LEFTJENA  (Gr.  leptos,  slender).     A  genus  of  Brachiopods. 

LINGULA  (Lat.  lingula,  a  little  tongue).     A  genus  of  Brachiopods, 

LYCOPODIACE^B  (Gr.  lupos,  a  wolf ;  pous,  foot).  The  group  of  Cryptogamic 
plants  generally  known  as  "Club-mosses." 

MACH^RACANTHUS  (Gr.  mackaira,  a  sabre;  zcantha,  thorn  or  spine).    An  ex- 
tinct genus  of  Fishes. 
MACHAIRODUS  (Gr.  machaira,  a  sabre  ;  odous,  tooth).     An  extinct  genus  of 

Garni  vora. 
MACROTHERIUM  (Gr.  makros,  long;  thenon.   beast).     An  extinct  genus  cf 

Edentata. 
MACRURA  (Gr.  makros,  long ;  oura,  tail).    A  tribe  of  Decapod  Crustaceans  with 

long  tails  (e.g.,  the  Lobster,  Shrimp,  &c.) 
MAMMALIA  (Lat.  mamma,  the  breast).    The  class  of  Vertebrate  animals  which 

suckle  their  young. 
MANDIBLE  (Lat.  mandibulum,  a  jaw).    The  upper  pair  of  jaws  in  Insects ;  also 

applied  to  one  of  the  pairs  of  jaws  in  Crustacea  and  Spiders,  to  the  beak  of 

Cephalopods,  the  lower  jaw  of  Vertebrates,  &c. 
MANTLE.     The  external  integument  of  most  of  the  Mollusca,  which  is  largely 

developed,  and  forms  a  cloak  in  v/hich  the  viscera  are  protected.     Techni- 
cally called  the  "  pallium." 

MAN  us  (Lat.  the  hand).    The  hand  of  the  higher  Vertebrates. 
MARSIPOBRANCHII  (Gr.  marsipos,   a  pouch ;    bragchia,  gill).    The  order  of 

Fishes  comprising  the  Hag-fishes  and  Lampreys,  with  pouch-like  gills. 
MARSUPIALIA  (Lat.  marsupium,  a  pouch).    An  order  of  Mammals  in  which  tho 

females  mostly  have  an  abdominal  pouch  in  which  the  young  are  carried. 
MASTODON  (Gr.  mastos,  nipple  ;  odous,  tooth).     An  extinct  genus  of  Elephant- 
ine Mammals. 
MEGALONYX  (Gr.  megas,  great ;  onux,  nail).     An  extinct  genus  of  Edentate 

Mammals. 
MEGALOSAURUS  (Gr.  megas,  great ;  saara,  lizard).     A  genus  of  Deinosaurian 

Reptiles. 
MEGATHERIUM  (Gr.   megas,  great ;  therion,   beast).      An  extinct    genus   of 

Edentata. 

MESOZOIC  (Gr.  mesos,  middle  ;  and  zoe,  life).    The  Secondary  period  in  Geolo.ory. 
MICROLESTES  (Gr.  mikros,  little  ;  lestes,  thief).     An  extinct  genus  of  Triassic 

Mammals. 
MILLEPORA  (Lat.  mille,  one  thousand  ;  porus,  a  pore).     A  genus  of  "  Tabulate 

Corals." 

MIOCENE  (Gr.  melon,  less  ;  kainos,  new).     The  Middle  Tertiary  period. 
MOLARS  (Lat.  mola,  a  mill).     The  "  grinders"  in  man,  or  the  teeth  in  diphjo 

dont  Mammals  which  are  not  preceded  by  milk-teeth. 
MOLLUSCA  (Lat.  mollis,  soft).     The  sub-kingdom  which  includes  the  Shell-fish 

proper,  the  Polyzoa,  the  Tunicata,  and  the  Lamp-shells  ;  so  called  from  the 
generally  soft  nature  of  their  bodies. 

MOLLUSCOIDA  (Mollusca  ;  Gr.  eidos,  form).     The  lower  division  of  the  Mol- 
lusca, comprising  the  Polyzoa,  Tunicata,  and  Brachiopoda. 
MONOGRAPTUS  (Gr.  monos,  single  ;  yrapho,  I  write).     A  genus  of  Graptolites. 
MYLODON  (Gr.  mulos,  a  mill ;  odous,  tooth).      An  extinct  genus  of  Edentate 

Mammals. 

MYRIAPODA  or  MYRIOPODA  (Gr.  murios,  ten  thousand  ;  podes,  feet).  A  class 
ot  Arthropoda  comprising  the  Centipedes  and  their  allies,  characterii-ed  by 
their  numerous  feet. 


GLOSSARY.  389 

NATATORES  (Lat.  nare,  to  swim).     The  order  of  the  Swimming  Birds. 

NATATORY  (Lat.  nare,  to  swim).     Formed  for  swimming. 

NAUTILOID.     Resembling  the  shell  of  the  Nautilus  in  shape. 

UERVURES  (Lat.  nenus,  a  sinew).  The  ribs  which  support  the  membranous 
wings  of  insects. 

HEUROPTERA  (Gr.  neuron,  a  nerve  ;  pteron,  a  wing).  An  order  of  Insects  char- 
acterised by  four  membranous  wings  with  numerous  reticulated  nervures 
(e.g.,  Dragon-flies). 

NEUROPTERIS  (Gr.  neuron,  a  nerve  ;  pteris,  a  fern).  An  extinct  genus  of 
Ferns. 

NOTHOSAURUS  (Gr.  nothos,  spurious;  saury,,  lizard).  A  genus  of  Plesiosaurian 
Reptiles. 

NOTOCHORD  (Gr.  notos,  back  ;  chorde,  string).  A  cellular  rod  which  is  devel- 
oped in  the  embryo  of  Vertebrates  immediately  beneath  the  spinal  cord,  and 
which  is  usually  replaced  in  the  adult  by  the  vertebral  column.  Often  it  is 
spoken  of  as  the  "  chorda  dorsalis." 

NUDIBRANCHIATA  (Lat.  nudus,  naked;  and  Gr.  bragcliia,  gill).  An  order  of 
the  Gasteropoda  in  which  the  gills  are  naked. 

NUMMULINA  (Lat.  nummus,  a  coin).  A  genus  of  Foraminifera,  comprising  the 
coin-shaped  "  Nummulites." 

OBOLELLA  (Lat.  dim.  of  ololus,  a  small  coin).     An  extinct  genus  of  BracL:> 

pods. 

OCCIPITAL.     Connected  with  the  occiput,  or  the  back  part  of  the  head. 
OCEANIC.     Applied  to  animals  which  inhabit  the  open  ocean  (  =  pelagic).1 
ODONTOPTERYX  (Gr.  odous,  tooth ;  pterux,   wing).     An  extinct   genus  of 

Birds. 
ODONTORNITHES  (Gr.  odous,  tooth ;  ornis,  bird).    The  extinct  order  of  Birds, 

comprising  forms  with  distinct  teeth  in  sockets. 
OLIGOCENE  (Gr.  oligos,  few ;  kainos,  new).    A  name  used  by  many  Continental 

geologists  as  synonymous  with  the  Lower  Miocene. 

OPHIDIA  (Gr.  ophis,  a  serpent).    The  order  of  Reptiles  comprising  the  Snakec. 
OPHIUROIDEA  (Gr.  ophis,  snake  ;  oura,  tail ;  eidos,  form ).    An  order  of  Echino- 

dermata,  comprising  the  Brittle-stars  and  Sand-stars. 
ORNITHOSCELIDA  (Gr.  ornis,  bird ;  skelos,  leg).     Applied  by  Huxley  to  the 

Deinosaurian  Reptiles,  together  with  the  genus  Compsoynathus,  on  account 

of  the  bird-like  character  of  their  hind-limbs. 
ORTHIS  (Gr.  orthos,  straight).   A  genus  of  Brachiopods,  named  in  allusion  to  the 

straight  hinge-line. 
ORTHOCERATID.E  (Gr.  orlhos,  straight ;  keras,  horn).    A  family  of  the  Naw- 

tilidce,  in  which  the  shell  is  straight,  or  nearly  so. 
ORTHOPTERA  (Gr.  orthos,  straight ;  pteron,  wing).     An  order  of  Insects. 
OSTEOLEPIS  (Gr.  osteon,  bone ;  lepis,  scale).      An  extinct  genus  of  Ganoid 

Fishes. 
OSTRACODA  (Gr.  ostrakon,  a  shell).     An  order  of  small  Crustaceans  which  are 

enclosed  in  bivalve  shells. 

OTODUS  (Gr.  ota,  ears  ;  odous,  tooth).     An  extinct  genus  of  Sharks. 
OUDENODON  (Gr.  ouden,  none ;  odous,  tooth).     A  genus  of  Dicynodont  Rep- 
tiles. 
OVIBOS  (Lat.  ovis,  sheep  ;  bos,  ox).     The  genus  comprising  the  Musk-ox. 

PACHYDERMATA  (Gr.  pacJtus,  thick  ;  derma,  skin).  An  old  Mammalian  order 
constituted  by  Cuvier  lor  the  reception  of  the  Rhinoceros,  Hippopotamus, 
Elephant,  &c. 

PAL^EASTER  (Gr.  palaios,  ancient ;  aster,  star).  An  extinct  genus  of  Star- 
h'shes. 

PAL^EOCARIS  (Gr.  palaios,  ancient ;  karis,  shrimp).  An  extinct  genus  of  Deca- 
pod Crustaceans. 

PALAEOLITHIC  (Gr.  palaios,  ancient ;  lithos,  stone).  Applied  to  the  rude  stone 
implements  of  the  earliest  known  races  of  men,  to  the  men  who  made  these 
implements,  or  to  the  period  at  which  they  were.  made. 


390  GLOSSARY. 

PALAEONTOLOGY  (Gr.  palaios,  ancient ;  and  logos,  discourse).     The  science  of 

fossil  remains  or  of  extinct  organised  beings. 
PAL^EOPHIS  (Gr.  palaios,  ancient ;  ophis,  serpent).      An  extinct  genus   of 

Snakes. 
PAL^OSAURUS  (Gr.  palaios,  ancient ;  saura,  lizard).     A  genus  of  Thecodont 

Reptiles. 
PAL^OTHEREDJE  (Gr.   palaios,  ancient ;   ther,  beast).     A   group  of  Tertiary 

Ungulates. 
PALEOZOIC  (Gr.  palaios,  ancient ;  and  zoe,  life).     Applied  to  the  oldest  of  the 

great  geological  epochs. 

PARADOXIDES  (Lat.  paradoxiis,  marvellous).     A  genus  of  Trilobites. 
PATAGIUM  (Lat.  the  border  of  a  dress).     Applied  to  the  expansion  of  the  in- 
tegument by  which  Bats,  Flying  Squirrels,  and  other  animals  support  them- 
selves in  the  air. 

PECOPTERIS  (Gr.  peko,  I  comb ;  pteris,  a  fern).     An  extinct  genus  of  Ferns. 
PECTEN   (Lat.   a  comb).     The  genus  of   Bivalve   Molluscs  comprising  the 

Scallops. 

PECTORAL  (Lat.  pectus,  chest).     Connected  with,  or  placed  upon,  the  chest. 
PENTACRINUS  (Gr.  penta,  five  ;    krinon,  lily).    A  genus  of  Crinoids  in  which 

the  column  is  five-sided. 

PENTAMERUS  (Gr.  penta,  five ;  mews,  part).    An  extinct  genus  of  Brachiopods. 
PSNTREMITES  (Gr.  penta,  five ;  trema,  aperture).     A  genus  of  Blastoidea,  so 

named  in  allusion  to  the  apertures  at  the  summit  of  the  calyx. 
PERENNIBRANCHIATA  (Lat.  perennis,  perpetual  ;  Gr.  bragchia,  gill).     Applied 

to  those  Amphibia  in  which  the  gills  are  permanently  retained  throughout 

life. 
PERISSODACTYLA  (Gr.  perissos,  uneven ;  daktulos,  finger).     Applied  to  those 

Hoofed  Quadrupeds  ( Ungulata)  in  which  the  feet  have  an  uneven  number  of 

toes. 

PETALOID.     Shaped  like  the  petal  of  a  flower. 

PHACOPS  (Gr.  phake,  a  lentil ;  ops,  the  eye).     A  genus  of  Trilobites. 
PHALANGES  (Gr.  phalanx,  a  row).     The  small  bones  composing  the  digits  of 

the  higher  Vertebrata.     Normally  each  digit  has  three  phalanges. 
PHANEROGAMS  (Gr.  phaneros,  visible  ;  gamos,  marriage).    Plants  which  have 

the  organs  of  reproduction  conspicuous,  and  which  bear  true  flowers. 
PHARYNGOBRANCHII  (Gr.  pharugx,  pharynx;  bragchia,  gill).     The  order  of 

Fishes  comprising  only  the  Lancelet. 
PHASCOLOTHERIUM  (Gr.  phaskolos,  a  pouch ;  therion,  a  beast).    A  genus  of 

Oolitic  Mammals. 
PHRAGMACONE  (Gr.  phragma,  a  partition  ;  and  konos,  a  cone).    The  chambered 

portion  of  the  internal  shell  of  a  Belemnite. 

PHYLLOPODA  (Gr.  phullon,  leaf ;  and  pous,  foot).     An  order  of  Crustacea. 
PINNATE  (Lat.  pinna,  a  feather).     Feather-shaped ;  or  possessing  lateral  pro- 
cesses. 
PINNIGRADA  (Lat.  pinna,  a  feather  ;  gradior,  I  walk).     The  group  of  Carniv- 

ora,  comprising  the  Seals  and  Walruses,  adapted  for  an  aquatic  life.     Often 

called  Pinnipedia. 

PINNULE  (Lat.  dim.  of  pinna).    The  lateral  processes  of  the  arms  of  Crinoids. 
PISCES  (Lat.  piscis,  a  fishV     The  class  of  Vertebrates  comprising  the  Fishes. 
PLACOID  (Gr.  plax,  a  plate;  eidos,  form).     Applied  to  the  irregular  bony 

plates,   grains,   or  spines  which  are  found  in  the  skin  of  various  fishes 

( Elasmobranchii). 
PLAGIOSTOMI  (Gr.  plagios,  transverse  ;  stoma,  mouth).    The  Sharks  and  Rays, 

in  which  the  mouth  is  transverse,  and  is  placed  on  the  under  surface  of  the 

head. 

PLATYCERAS  (Gr.  platus,  broad  ;  keras,  horn).     A  genus  of  Univalve  Molluscs. 
PLATYCRINUS  (Gr.  platus,  broad ;  krinon,  lily).     A  genus  of  Crinoidea. 
PLATYRHINA  (Gr.  platus,  broad  ;  rhines,  nostrils).  A  group  of  the  Quadrumana. 
PLATYSOMUS  (Gr.  platus,  wide  ;  soma,  body).     A  genus  of  Ganoid  Fishes. 
PLEISTOCENE  (Gr.  pleistos,  most ;  kainos,  new).     Often  used  as  synonymous 

with  "  Post-Pliocene." 


GLOSSARY.  391 

PLEUROTOMARIA  (Gr.  pleura,  the  side ;  tomt,  notch).     A  genus  of  Univalve 

shells. 

PLIOCENE  (Gr.  pleion,  more  ;  kainos,  new).     The  later  Tertiary  period. 
PLIOPITHECUS  (Gr.  pleion,  more  ;  pithekos,  ape).  An  extinct  genus  of  Monkeys. 
PLIOSAURUS  (Gr.  pleion,  more  ;  saura,  lizard).      A  genus  of  Plesiosaurian 

Reptiles. 
POLYCYSTINA  (Gr.  polus,  many  ;  and  kustis,  a  cyst).     An  order  of  Protozoa 

with  foraminated  siliceous  shells. 

POLYPARY.     The  hard  chitinous  covering  secreted  by  many  of  the  Hydrozoa. 
POLYPE  (Gr.  polus,  many  ;  pous,  foot).     Restricted  to  the  single  individual  of 

a  simple  Actinozoon,  such  as  a  Sea-anemone,  or  to  the  separate  zooids  of  a 

compound  Actinozoon.     Often  applied  indiscriminately  to  any  of  the  Coelen- 

terata,  or  even  to  the  Polyzoa. 
POLYPORA  (Gr.  polus,   many;  poros,   a  passage).     A  genus  of  Lace-corals 

(Fenestellidce}. 
POLYTHALAMOUS  (Gr.  polus  ;  and  thalamos,  chamber).   H aving  many  chambers  ; 

applied  to  the  shells  of  Foraminifcra  and  Cephalopoda. 

POLYZOA  (Gr.  polus;  and  zoon,  animal).     A  division  of  the  Molluscoida  com- 
prising compoiind  animals,  such  as  the  Sea-mat— sometimes  called  Bryozoa. 
PORIFERA  (Lat.  porus,  a  pore  ;  and  fero,  I  carry).     Sometimes  used  to  desig- 
nate the  Foramini/era,  or  the  Sponges. 
PR^MOLARS  (Lat.  prce,  before ;  molar  es,  the  grinders).     The  molar  teeth  of 

Mammals  which  succeed  the  molars  of  the  milk-set  of  teeth.     In  man,  the 

bicuspid  teeth. 
PROBOSCIDEA  (Lat.  proboscis,  the  snout).     The  order  of  Mammals  comprising 

the  Elephants. 
PROCCELOUS  (Gr.  j.ro,  before  ;  koilps,  hollow).    Applied  to  vertebrae  the  bodies 

of  which  are  hollow  or  concave  in  front. 
PRODUCTA  (Lat.  productus,  drawn  out  or  extended).      An  extinct  genus  of 

Brachiopods,  in  which  the  shell  is  "  eared,"  or  has  its  lateral  angles  drawn 

out. 

PROTICHNITES  (Gr.  protos,  first ;  ichnos,  footprint).     Applied  to  certain  im- 
pressions in  the  Potsdam  sandstone  of  North  America,  believed  to  have 

been  produced  by  large  Crustaceans. 

PROTOPHYTA  (Gr.  protos  ;  and  phuton,  plant).     The  lowest  division  of  plants. 
PROTOPLASM  (Gr.  protos  ;  and  plasso,  I  mould).     The  elementary  basis  of  or- 
ganised tissues.     Sometimes  used  synonymously  for  the  "  sarcode  "  of  the 

Protozoa. 
PROTOROSAURUS  or  PROTEROSAURUS  (Gr.  protos,  h'rst ;  orao,  I  see  or  discover ; 

saura,  lizard  :  or  proteros,  earlier ;  saura,  lizard).       A  genus  of  Permian 

lizards. 
PROTOZOA  (Gr.  protos;  and  zoon,  animal).     The  lowest  division  of  the  animal 

kingdom. 
PSAMMODUS  (Gr.  psammos,  sand  ;  odous,  tooth).     An  extinct  genus  of  Cestra- 

ciont  Sharks. 
PSEUDOPODIA  (Gr.  pseudos,  falsity ;  and  pous,  foot).     The  extensions  of  the 

body-substance  which  are  put  forth  by  the  Rhizopoda  at  will,  and  which 

serve  for  locomotion  and  prehension. 
PSILOPHYTON  (Gr.  psilos,  bare  ;  phuton,  plant).     An  extinct  genus  of  Lyco- 

podiaceous  plants. 
PTERANODON  (Gr.  pteron,  wing  ;  a,  without ;  odous,  tooth).    A  genus  of  Ptero- 

saurian  Reptiles. 

PTERASPIS  (Gr.  pteron,  wing ;  aspis,  shield).     A  genus  of  Ganoid  Fishes. 
PTERICHTHYS  (Gr.  pteron,  wing  ;  ichthus,  fish).     A  genus  of  Ganoid  Fishes. 
PTERODACTYLUS  (Gr.  pteron,  wing ;  daktulos,  finger).   A  genus  of  Pterosaurian 

Reptiles. 
PTEROPODA  (Gr.  pteron,  wing  ;  and  pous,  foot).    A  class  of  the  Mollusca  which 

swim  by  means  of  fins  attached  near  the  head. 

PTEROSAURIA  (Gr.  pteron,  wing  ;  saura,  lizard).    An  extinct  order  of  Reptiles. 
PTILODICTYA  (Gr.  ptilon,   a  feather  ;  diktuon,  a  net).     An  extinct  genus  of 

Polyzoa. 


392  GLOSSARY. 

PTYCHOCERAS  (Gr.  ptucM,  a  fold ;  keras,  a  horn).     A  genus  of  Ammonitidce. 

PULMONATE.     Possessing  lungs. 

PYEIFOBM  (Lat.  pyrus,  a  pear;  and  forma,  form).     Pear-shaped. 

QUADRUMANA  (Lat.  quatuor,  four  ;  mantis,  hand).  The  order  of  Mammals 
comprising  the  Apes,  Monkeys,  Baboons,  Lemurs,  &c. 

RADIATA  (Lat.  radius,  a  ray).  Formerly  applied  to  a  large  number  of  animals 
which  are  now  placed  in  separate  sub-kingdoms  (e.g.,  the  Ccelenterata,  the 
Echinodermata,  the  Infusoria,  &c.) 

RADIOLARIA  (Lat.  radius,  a  ray).     A  division  of  Protozoa. 

RAMUS  (Lat.  a  branch).  Applied  to  each  half  or  branch  of  the  lower  jaw,  or 
mandible,  of  Vertebrates. 

RAPTORES  (Lat.  rapto,  I  plunder).     The  order  of  the  Birds  of  Prey. 

RASORES  (Lat.  rado,  I  scratch).  The  order  of  the  Scratching  Birds  (Fowls, 
Pigeons,  &c.) 

RECEPTACULITES  (Lat.  receptaculum,  a  storehouse).  An  extinct  genus  of 
Protozoa. 

REPTILIA  (Lat.  repto,  I  crawl).  The  class  of  the  Vertebrata  comprising  the 
Tortoises,  Snakes,  Lizards,  Crocodiles,  &c. 

RETEPORA  (Lat.  rete,  a  net ;  porus,  a  pore).    A  genus  of  Lace- corals  (Polyzoa). 

RHAMPHORHYNCHUS  (Gr.  rhamphos,  beak  ;  rhugchos,  nose).  A  genus  of 
Pterosaurian  Reptiles. 

RHINOCEROS  (Gr.  rhis,  the  nose  ;  keras,  horn).  A  genus  of  Hoofed  Quadru- 
peds. 

RHIZOPODA  (Gr.  rhtza,  a  root ;  and  potts,  foot).  The  division  of  Protozoa  com- 
prising all  those  which  are  capable  of  emitting  pseudopodia. 

RHYNCHOLITES  (Gr.  rhugchos,  beak  ;  and  lithos,  stone).  Beak-shaped  fossils 
consisting  of  the  mandibles  of  Cephalopoda. 

RHYNCHONELLA  (Gr.  rhugchos,  nose  or  beak).    A  genus  of  Brachiopods. 

RODENTIA  (Lat.  rodo,  I  gnaw).  An  order  of  the  Mammals ;  often  called  Glires 
(Lat.  glis,  a  dormouse). 

ROTALIA  (Lat.  rota,  a  wheel).     A  genus  of  Foraminifera. 

RUGOSA  (Lat  rugosus,  wrinkled).     An  order  of  Corals. 

RUMINANTIA  (Lat.  ruminor,  I  chew  the  cud).  The  group  of  Hoofed  Quadru- 
peds (Ungulata)  which  "  ruminate  "  or  chew  the  cud. 

SARCODE  (Gr.  sarx,  flesh  ;  eidos,  form).  The  jelly-like  substance  of  which  the 
bodies  of  the  Protozoa  are  composed.  It  is  an  albuminous  body  containing 
oil-granules,  and  is  sometimes  called  "animal  protoplasm." 

SAURIA  (Gr.  saura,  a  lizard).  Any  lizard-like  Reptile  is  often  spoken  of  as  a 
"Saurian;"  but  the  term  is  sometimes  restricted  to  the  Crocodiles  alone, 
or  to  the  Crocodiles  and  Lacertilians. 

SAUROPTERYGIA  (Gr.  saura  ;  pteriix,  wing).  An  extinct  order  of  Reptiles, 
called  by  Huxley  Plesiosauria,  from  the  typical  genus  Plesiosaurus. 

SAURUR^  (Gr.  saura;  oura,  tail).  The  extinct  order  of  Birds  comprising 
only  the  Archceopteryx. 

SCANSORES  (Lat.  scando,  I  climb).  The  order  of  the  Climbing  Birds  (Parrots, 
Woodpeckers,  &c.) 

SCAPHITES  (Lat.  scapha,  a  boat).     A  genus  of  the  Ammonitidce. 

SCOLITHUS  (Gr.  skolex,  a  worm  ;  lithos,  a  stone).  The  vertical  burrows  of  sea- 
worms  in  rocks. 

SCUTA  (Lat.  scutum,  a  shield).  Applied  to  any  shield-like  plates  ;  especially  to 
those  which  are  developed  in  the  integument  of  many  Reptiles. 

SELACHIA  or  SELACHII  (Gr.  selachos,  a  cartilaginous  fish,  probably  a  shark). 
The  sub-order  of  Elasmobranchii  comprising  the  Sharks  and  Dog-fishes. 

SEPIOSTAIRE.  The  internal  shell  of  the  Sepia,  commonly  known  as  the 
"cuttle-bone." 

SEPTA.     Partitions. 

SERPENTIFORM.     Resembling  a  serpent  in  shape. 

SERTULARIDA  (Lat.  sertum,  a  wreath).     An  order  of  Hydrozoa. 


GLOSSARY.  393 

SESSILE  (Lat.  sedo,  I  sit).    Not  supported  upon  a  stalk  or  peduncle;  attached 

by  a  base. 

SETJE  (Lat.  bristles).     Bristles  or  long  stiff  hairs. 
SIGILLARIOIDS  (Lat.  sigilla,  little  images).    A  group  of  extinct  plants  of  which 

Sigillaria  is  the  type,  so  called  from  the  seal-like  markings  on  the  bark. 
SILICEOUS  (Lat.  silex,  flint).     Composed  of  flint. 

SINISTRAL  (Lat.  sinistra,  the  left  hand).     Left-handed  ;  applied  to  the  direc- 
tion of  the  spiral  in  certain  shells,  which  are  said  to  be  "  reversed." 
SIPHON  (Gr.   a  tube).      Applied  to  the  respiratory  tubes  in  the  Mollusca  ; 

also  to  other  tubes  of  different  functions. 
SIPHONIA  (Gr.  siphon,  a  tube).    A  genus  of  fossil  Sponges. 
SIPHONOSTOMATA  (Gr.  siphon  ;  and  stoma,  mouth).     The  division  of  Gastero- 

podous  Molluscs  in  which  the  aperture  of  the  shell  is  not  "  entire,"  but 

possesses  a  notch  or  tube  for  the  emission  of  the  respiratory  siphon. 
SIPHUNCLE  (Lat.  siphunculus,  a  little  tube).     The  tube  which  connects  to- 
gether the  various  chambers  of  the  shell  of  certain  Cephalopoda  (e.g.,  the 

Pearly  Nautilus). 
SIRENIA  (Gr.  seiren,  a  mermaid).     The  order  of  Mammalia  comprising  the 

Dugongs  and  Manatees. 
SIVATHERIUM  (Siva,  a  Hindoo  deity ;  Gr.  therion,  beast).     An  extinct  genus 

of  Hoofed  Quadrupeds. 
SOLIDUNGULA  (Lat.  solidus,  solid  ;  ungula,  a  hoof).     The  group  of  Hoofed 

Quadrupeds  comprising  the  Horse,  Ass,  and  Zebra,  in  which  each  foot  has 

only  a  single  solid  hoof.     Often  called  Solipedia. 
SPHENOPTERIS  (Gr.  sphen,  a  wedge ;  pteris,  a  fern).     An  extinct  genus  of 

ferns. 

SPICULA  (Lat.  spiculum,  a  point).     Pointed  needle-shaped  bodies. 
SPIRIFERA  (Lat.  spira,  a  spire  or  coil ;  fero,  I  carry).     An  extinct  genus  of 

Brachiopods,  with  large  spiral  supports  for  the  "arms." 
SPIRORBIS  (Lat.  spira,  a  spire  ;  orbis,  a  circle).     A  genus  of  tube-inhabiting 

Annelides,  in  which  the  shelly  tube  is  coiled  into  a  spiral  disc. 
SPONGIDA  (Gr.  spoggos,  a  sponge).     The  division  of  Protozoa  commonly  known 

as  sponges. 
STALACTITES  (Gr.  stalasso,  I  drop).     Icicle-like  encrustations  and  deposits  of 

lime,  which  hang  from  the  roof  of  caverns  in  limestone. 
STALAGMITE  (Gr.  stalagma,  a  drop).    Encrustations  of  lime  formed  on  the  floor 

of  caverns  which  are  hollowed  out  of  limestone. 
STIGMARIA  (Gr.  stigma,  a  mark  made  with  a  pointed  instrument).     A  genus 

founded  on  the  roots  of  various  species  of  Sigillaria. 
STRATUM  (Lat.  stratus,  spread  out ;  or  stratum,  a  thing  spread  out).     A  layer 

of  rock. 
STROMATOPORA  (Gr.  stroma,  a  thing  spread  out ;  poros,  a  passage  or  pore).    A 

Palaeozoic  genus  of  Protozoa. 
STROPHOMENA  (Gr.  strophao,  I  twist ;   men$,  moon).      An  extinct  genus  of 

Brachiopods. 

SUB-CALCAREOUS.     Somewhat  calcareous. 
SUB-CENTRAL.     Nearly  central,  but  not  quite. 

SUTURE  (Lat.  suo,  I  sew).  The  line  of  junction  of  two  parts  which  are  immov- 
ably connected  together.  Applied  to  the  line  where  the  whorls  of  a  univalve 

shell  join  one  another  ;  also  to  the  lines  made  upon  the  exterior  of  the  shell 

of  a  chambered  Cephalopod  by  the  margins  of  the  septa. 
SYRINGOPORA  (Gr.  surigx,  a  pipe  ;  poros,  a  pore).    A  genus  of  Tabulate  Corals. 

TABULAE  (Lat.  tabula,  a  tablet).  Horizontal  plates  or  floors  found  in  some 
Corals,  extending  across  the  cavity  of  the  "  theca  "  from  side  to  side. 

TEGUMENTARY  (Lat.  tegumentum,  a  covering).  Connected  with  the  integu- 
ment or  skin. 

TELEOSAURUS  ^Gr.  teleios,  perfect ;  saura,  lizard).  An  extinct  genus  of  Cro- 
codilian Reptiles. 

TFLKOSTEI  (Gr.  teleios,  perfect;  osteon,  bone).  Ths  order  of  the  "Bony 
Fishes." 


394  GLOSSARY. 

TELSON  (Gr.  a  limit).  The  last  joint  in  the  abdomen  of  Crustacea;  va- 
riously regarded  as  a  segment  without  appendages,  or  as  an  azygous 
appendage. 

TENTACULITES  (Lat.  tentaculum,  a  feeler).    A  genus  of  Pteropoda, 

TEREBRATULA  (Lat.  tcrebratus,  bored  or  pierced).  A  genus  ot  Brachiopoda,  so 
called  in  allusion  to  the  perforated  beak  of  the  ventral  valve. 

TEST  (Lat.  testa,  shell).  The  shell  of  Mollusca,  which  are  for  this  reason 
sometimes  called  "  Teslacea  ;  "  also,  the  calcareous  case  of  Echinoderms  ; 
also,  the  thick  leathery  outer  tunic  in  the  Tunicata. 

TESTACEOUS.     Provided  with  a  shell  or  hard  covering. 

TESTUDINID.E  (Lat.  testudo,  a  tortoise).     The  family  of  the  Tortoises. 

TETRABRANCHIATA  (Gr.  tetra,  four  ;  bragchia,  gill).  The  order  of  Cephalopoda 
characterised  by  the  possession  of  four  gills. 

TEXTULARIA  (Lat.  textilis,  woven).     A  genus  of  Foraminifera. 

THECA  (Gr.  thekt,  a  sheath).     A  genus  of  Pteropods. 

THECODONTOSAURUS  (Gr.  thibi,  a  sheath  ;  odous,  tooth ;  saura,  lizard).  A 
genus  of  "Thecodont  "  Reptiles,  so  named  in  allusion  to  the  fact  that  the 
teeth  are  sunk  in  distinct  sockets. 

THERIODONT  (Gr.  tlierion,  a  beast ;  odous,  tooth).  A  group  of  Reptiles  so 
named  by  Owen  in  allusion  to  the  Mammalian  character  of  their  teeth. 

THORAX  (Gr.  a  breastplate).    The  region  of  the  chest. 

THYLACOLEO  (Gr.  thulakos,  a  pouch  ;  leo,  a  lion).  An  extinct  genus  of  Mar- 
supials. 

TRIGONIA  (Gr.  treis,  three  ;  gonia,  angle).    A  genus  of  Bivalve  Molluscs. 

TRIGONOCARPON  (Gr.  treis,  three ;  gonia.  angle  ;  karpos,  fruit).  A  genus 
founded  on  fossil  fruits  of  a  three-angled  form. 

TRILOBITA  (Gr.  treis,  three  ;  lobos,a.  lobe).     An  extinct  order  of  Crustaceans. 

TRINUCLEUS  (Lat.  tris,  three  ;  nucleus,  a  kernel).     A  genus  of  Trilobites. 

TROGONTHERIUM  (Gr.  trogo,  I  gnaw ;  therion,  beast).  An  extinct  genus  of 
Beavers. 

TUBICOLA  (Lat.  tuba,  a  tube;  and  cofo,  I  inhabit).  The  order  of  Annelida 
which  construct  a  tubular  case  in  which  they  protect  themselves. 

TUBICOLOUS.     Inhabiting  a  tube. 

TUNICATA  (Lat.  tunica,  a  cloak).  A  class  of  Molluxcoida  which  are  enveloped 
in  a  tough  leathery  case  or  "  test." 

TUKBFNATED  (Lat.  turbo,  a  top).     Top-shaped  ;  conical  with  a  round  base. 

TCRRILITES  (Lat,  turris,  a  tower).     A  genus  of  the  Ammonitidce. 

UMBO  (Lat.  the  boss  of  a  shield).     The  beak  of  a  bivalve  shell. 

UNGUICULATE  (Lat.  unguis,  nail).     Furnished  with  claws. 

UNGULATA  (Lat.  ungula,  hoof).   The  order  of  Mammals  comprising  the  Hoofed 

Quadrupeds. 

UNGULATE.     Furnished  with  expanded  nails  constituting  hoofs. 
UNILOCULAR  (Lat.  unus,  one ;  and  loculus.  a  little  purse).     Possessing  a  single 

cavity  or  chamber.     Applied  to  the  shells  of  Foraminifera  and  Mollusca. 
UNIVALVE  (Lat.  unus,  one;  valvw,  folding-doors).     A  shell  composed  of  a 

single  piece  or  valve. 
URODELA  (Gr.  oura,  tail ;  delos,  visible).    The  order  of  the  Tailed  Amphibians 

(Newts,  &c.) 

VENTRAL  (Lat.  venter,  the  stomach).     Relating  to  the  inferior  surface  of  the 

body. 
VENTRICULITES  (Lat.  ventriculum,  a  little  stomach).     A  genus  of  siliceous 

Sponges. 

VERMIFORM  (Lat.  i-ermis,  worm  ;  and  forma,  form).     Worm-like. 
VERTEBRA  (Lat.  verto,  I  turn).     One  of  the  bony  segments  of  the  vertebral 

column  or  backbone. 
VERTEBRATA  (Lat.  vertebra,  a  bone  of  the  back,  from  vertere,  to  turn).     The 

division  of  the  Animal  Kingdom  roughly  characterised  by  the  possession  of 

a  backbone. 
VESICLE  (Lat.  resica,  a  bladder).     A  little  sac  or  cyst. 


GLOSSARY.  395 

WHORL.     The  spiral  turn  of  a  univalve  shell. 

XIPHOSURA  (Gr.  xiphos,  a  sword  ;  and  ov.ra,  tail).  An  order  of  Crustacea, 
comprising  tbe  LinwUi  or  King-Crabs,  characterised  by  their  long  sword- 
like  tails. 

XYLOBIUS  (Gr.  xuton,  wood ;  bios,  life).  An  extinct  genus  of  Myriapods, 
named  in  allusion  to  the  fact  that  the  animal  lived  on  decaying  wood. 

ZAPHRENTIS  (proper  name).     A  genus  of  Rugose  Corals. 

ZEUGLODONTID^E  (Gr.  zeugle,  a  yoke  ;  odons,  a  tooth).  An  extinct  family  of 
Cetaceans,  in  which  the  moiar  teeth  are  two-fauged,  and  look  as  if  composed 
of  two  parts  united  by  a  neck. 

ZOOPHYTE  (Gr.  zoon,  animal ;  phuton,  plant).  Loosely  applied  to  many  plant- 
like  animals,  such  as  Sponges,  Corals,  Sea-anemones,  Sea-mats,  &c. 


INDEX. 


Acadian  Group,  79. 

Acer,  308. 

Acervularia,  119,  173. 

Acidaspis,  123. 

Acorn-shells,  2(57. 

Acroculia,  128. 

Acrodus,  214,  242,  2:5;  nobilis,  242. 

Acrotreta,  110. 

Acroura,  120. 

Actinocrinus,  175. 

JEglina,  108. 

jEpiornis,  348. 

Agnoatus,  85-87,  108  ;  res,  85. 

Atces  malchis,  354. 

.4tecto,  108. 

Alethopteris,  136,  165,  196. 

^4  &7«?  (see  Sea-weed  s). 

Alligators,  218,  297. 

Alnus,  262. 

Amblypterus,  188;  macropterus,  188. 

Ainbonychia,  111. 

Ammonites.  187,  212-214,  237-239.  272; 
Humphresianu*,  238  ;  bifrons,  238. 

Ammonitidce,  239,  272,  285,  294. 

Amphibia,  189 ;  of  the  Carboniferous, 
189-191 ;  of  the  Permian,  200  ;  of  the 
Trias,  215-217  ;  of  the  Jurassic,  242;  of 
the  Miocene,  313. 

Amphicyon,  322. 

AmphUestes,  253. 

Amphinpongia,  118. 

Amphistegina,  311. 

Amphitherium,  253  255;  Prevostit,  254. 

Amphitragulus,  317. 

Amplexus,  173  ;  coralloides,  174. 

Ampyx,  108. 

Ananchytes,  266. 

Anchitherium,  301,  302. 

Ancyloceras,  272,  273;  Matkeronianut. 
273. 

Ancylotherium  Pen*elici,  315. 

Andrias  Scheachzeri,  313,  314. 

Angiosperni£,  261,  2(32. 

Animal  Kingdom,  divisions  of,  375-378. 

Anisopus,  206. 

-4wne2irfa,  of  the  Cambrian  period,  82, 
83 ;  of  the  Lower  Silurian,  107 ;  of  the 
Upper  Silurian,  122,  123  ;  of  the  De- 
vonian, 143,  144 ;  of  the  Carboniferous, 
178. 

Antntlaria,  137,  196,  207. 


Anomodontia,  220. 

^1  noplotlieridce,  302. 

Anoplotherium,  302,  303  ;  cownwne,  303 

Ant-eaters,  299,  315,  349.  350,  353. 

Antelopes,  317. 

Anthracosanrus  Ritsselli,  190. 

Anthrapalcemon  gracilis,  180. 

Antilocapra,  318. 

Antilope  quadricornis,  318. 

Antwerp  Crag,  325. 

Apes,  323. 

Apiocrinus,  231. 

Apteryx,  346,  348. 

Aqueous  rocks,  15 

Arachnida  of  the  Co.nl-measures,  181. 

Aralo-Caspian  Beds,  3*6. 

vlmttcaria,  2fi2. 

Araucarioxylon,  170. 

^4rca,  198;  antiqua,  199. 

Archceocidaris,  ITS. 

Archceocyathus,  82. 

Archoeopteryx,  252,   281;    macrnra,  252, 

253. 

Archceosphcerince,  75 
Archimedes,  184;   Wortheni,  183. 
Archiulus,  182. 

Arctic  regions,  Miocene  flora  of,  310. 
Arctocyon,  3('4. 
Arenaceous  rocks,  20. 
Arenicolites,  83  ;  didi/mus,  88. 
Arenig  rocks,  92,  94.  ' 
Argillaceous  rocks.  20. 
Armadillos,  299;  351,  353. 
Artiodactyle  Ungulates,  300,  317. 
Asaphus,  108;  tyrannas,  107,  luS. 
^.s'coceras,  130. 
Aspidella,  76. 
Aspidura  loricata,  210. 
Astarte  borealis,  338. 
Asterophyllites,  137,  19(5. 
Asterosteus,  152. 
Astrceidas,  231. 
Asfrceospongia,  118,  139. 
Astylospongia,  98 ;  prcenwrsa,  98. 
Athyris,  110,  127,  147,  198  ;  subtilita,  185. 
Atlantic  Ooze,  22,  23. 
Atrypa,  127;   congesta,  127;    hemisphce- 

rica,  127  ;  reticularis,  147,  148. 
Auger-shells,  293. 
Aurochs,  356. 
Aves  (.s-ec  Birds). 


r 


INDEX. 


397 


Aoicula,  235;  contorta,  211,  212;  socialis, 

21L 

"  Avicnla  contorta  Beds,"  2C4,  212. 
A  viculidce,  198,  269. 
Aviculopecten,  186. 
Axophylliim,  173. 
Aymestry  Limestone,  116,  117. 
Azoic  rocks,  67. 

Baculites,  273 ;  anceps,  274. 

Bagshot  and  Bracklesham  Beds,  287. 

Bakewellia,  198. 

Batcena,  315. 

Bala  Group,  93,  94. 

Bala  Limestone,  93. 

Balanidce,  267. 

Banksia,  262,  308. 

Barbadoes  Earth,  33. 

Barnacles,  267. 

Bath  Oolite,  227. 

Bats,  304,  322. 

Bears,  330,  359. 

Beaver,  322,  336. 

Beetles,  182,  311. 

Belemnitella  mucronata,  275. 

Belemnites,  214,  240,  274;  canaliculatus, 
241. 

Belemnitidce,  240,  285. 

Belemnoteuthis,  240. 

Belinurus,  179. 

Bellerophon,  111,  129, 148,  186 ;  Argo,  111. 

Belodon,  218;  Carolinensis,  219. 

Belosepia,  295. 

Beloteuthis  subcostata,  239,  240. 

Bembridge  Beds,  288. 

Beryx,  276  ;  Lewesiensis,  276. 

Beyrichia,  107  ;  complicata,  107. 

Bird's-eye  Limestone,  95,  96. 

Birds,  of  the  Trias,  222 ;  of  the  Jurassic, 
251-253 ;  of  the  Cretaceous,  281,  282 ;  of 
the  Eocene,  297 ;  of  the  Post-Pliocene, 
345-348. 

Bison  priscus,  356. 

Bituminous  Schists  of  Caithness,  36. 

Bivalves  (see  Lamellibranchiata). 

Black-lead  (see  Graphite). 

Black-River  Limestone,  95,  96. 

Blastoidea,  176 ;  of  the  Devonian,  143 ; 
of  the  Carboniferous,  176. 

BoidoB,  296. 

Bolderberg  Beds,  307. 

Bone-bed,  of  the  Upper  Ludlow,  116;  of 
the  Trias,  224. 

Bony  Fishes  (see  Teleostean  Fishes). 

Bos  primigenius,  356  ;  taurus,  356. 

Boulder-clay,  337. 

Bourgueticrinus,  266. 

Bovey-Tracy  Beds,  305,  309. 

Brachiopoda,  125 ;  of  the  Cambrian  rocks, 
87;  of  the  Lower  Silurian,  108-110;  of 
the  Upper  Silurian,  125-128;  of  the  De- 
vonian, 147,  148 ;  of  the  Carboniferous, 
184-186  ;  of  the  Permian,  198 ;  of  the 
Trias,  211 ;  of  the  Jurassic,  234 ;  of  the 
Cretaceous,  268  ;  of  the  Eocene,  292. 

Brachymetopus,  179. 

Brachyurous  Crustaceans,  180,  197. 

Bradford  Clay,  227. 

Breaks  in  the  Geological  and  Palaeonto- 
logical  record,  44-52. 

Breccia,  19. 

Brick-earths,  339. 

27 


Bridlington  Crag,  325,  326,  336. 
Brittle-stars  (see  Ophmroidea). 
Bronteus,  145. 
Brontotheridce,  316. 
Brontotherium  ingens,  316. 
Brontozoum,  206. 
Buccinum,  237. 
Bucklandia,  230. 
Bulimus,  294. 

Bunter  Sandstein,  203,  204,  206. 
Butterflies,  233,  311. 
Byssoarca,  198. 

Cainozoic  (see  Kainozoic). 

Calamaries,  239. 

Calamites,  165,  166,  196;  cannceformis, 
166. 

Calcaire  Grossier,  287,  288. 

Calcareous  rocks,  20-32 ;  Tufa,  21. 

Calciferous  Sand-rock,  95,  96. 

Calveria,  178. 

Calymene,  108,  123;  Blumenbachii,  107. 

Camarpphoria  globulina,  198. 

Cambrian  period,  77-90;  rocks  of,  in 
Britain,  77,  78;  in  Bohemia,  79;  in 
North  America,  79 ;  life  of,  80-90. 

Camelopardalidce,  317. 

Camels,  317,  354. 

Canis  lupus,  336 ;  Parisiensis,  304. 

Caradoc  rocks,  93,  94,  96. 

Carbon,  origin  of,  36. 

Carboniferous  Limestone,  157,  158. 

Carboniferous  period,  157-192 ;  rocks  of 
157-160  ;  life  of,  160-191. 

Carboniferous  Slates  of  Ireland,  135,  158, 
159. 

Carcharias,  275. 

Carcharodon,  295,  312  ;  productus,  313. 

Cardinia,  235. 

Cardiocarpon,  137. 

Cardiola,  128;  fibrosa.  128;  interrupta, 
128. 

Cardita,  213,  292 ;  planicosta,  292.  293. 

Cardium,  292;  Rhceticum,  211,  212. 

Caribou,  355. 

Carnivora,  of  the  Eocene,  304;  of  the 
Miocene,  322 ;  of  the  Pliocene,  330,  331 ; 
of  the  Post- Pliocene,  359-361. 

Caryocaris,  107,  108. 

Caryocrinus  ornatits,  106. 

Castor  fiber,  336. 

Ca^toroides  Ohioensis,  361. 

Catastrophism,  theory  of,  3. 

Catopterus,  214. 

Cauda-Galli  Grit,  135,  137. 

Caulopteris,  136,  164. 

Cave-bear,  360. 

Cave-deposits,  337,  339,  341-344. 

Cave-hyaena,  360. 

Cave-lion,  361. 

Caves,  formation  of,  341  ;  deposits  in,  342. 

Cavicornia,  317. 

Cement-stones,  31. 

Cephalaspis,  152 , 

Cephalopoda,  of  the  Cambrian  period,  88  ; 
of  the  Lower  Silurian,  111-114 ;  of  the 
Upper  Silurian,  130 ;  of  the  Devonian. 
149  ;  of  the  Carboniferous.  186,  187;  of 
the  Permian,  199;  of  the  Trias,  212  ;  of 
the  Jurassic,  237-240;  of  the  Cretaceous, 
272-275 ;  of  the  Eocene,  294 ;  of  the 
Miocene,  312. 


39* 


INDEX. 


Ceratiocaris,  108. 

Ceratites,  212-214;  nodosus,  212. 

Ceratodas,  214;  altu*,  214;  Foateri,  214, 

215,  255;  sermtus,  214. 
Ceriopora,  145  ;  Hamilconensw,  146. 
Cerithiurn,  213,  293;  hexagonum,  294. 
Cervidce,  of  the  Miocene  period,  317  ;  of 

the  Pliocene,  329  ;  of  the  Post-Pliocene, 

354,  355. 
Cervm,  317  ;  capreolus,  336, 354 :  elaphus, 

336,  354;  megaceros,  354,  355;  tarcm- 

dws,  354. 

Cestracion  Philippi,  188,  255. 
Cestracionts,  of  the  Devonian,  154;  of  the 

Carboniferous,    188 ;    of   the    Permian, 

199;  of  the  Trias,  214  ;  of  the  Jurassic, 

242  ;  of  the  Cretaceous,  275. 
Cetacea,  299  ;  of  the  Eocene,  299  ;  of  the 

Miocene,  315. 
Cetiosaurus,  249,  25 
Cheer opotamus,  302. 
Chwtetes,  105,  173  ;  tumidm,  174. 
Chain-coral,  119. 
Chalk,  259;  structure  of,  21-23 ;  Foramin- 

ifera  of,  22,  263;    origin  of.  23;   with 

flints,  259 ;  without  Hints,  259. 
Chama,  236. 

Chamcerops,  308  ;  Helvetica,  309. 
Chazy  Limestone,  95,  96. 
Cheiroptera,  of  the  Eocene,  304,  305 ;  of 

the  Miocene,  322. 
Cheir  other  mm,  215,  216. 
Cheirurus,  108,  123  ;  bitnucronatus,  124. 
Chelichnus  Duncani,  202. 
Chelone  Benstedi,  280 ;  planiceps,  251. 
Chelonia,   of  the  Permian,   202;    of  the 

Jurassic,  251 ;  of  the  Cretaceous,  28«  ; 

of  the  Eocene,  296;  of  the  Miocene,  213. 
Chemnitzia,  213. 
Cliemung  Group,  135,  136,  137. 
Chert,  34. 

Chillesford  Beds,  325,  326,  336. 
Chonetes,  127,  147,  184;    Hardrensia,  185. 
Chonophyllum,  173. 
Cidari*,  266. 

Cincinnati  Group,  95,  96. 
Cinnatnomurn  polymorphism,  309. 
Cinnamon-trees,  262,  290,  3u6,  308,  309. 
Cladodfus,  188. 
Claiborne  Beds,  289. 
Clathropora,  145 ;  intertexta,  146. 
Clay,  20 ;  Red,  origin  of,  35. 
Clay-ironstone,  nodules  of,  31. 
Cleidophonts,  111. 
Cleodora,  312. 
Ciimacograptus,  101,  119. 
Clinton  Formation,  116,  117. 
Clisiophylluin,  173. 
Clupeidte,  276. 

Clymenia,  149;  SedgwicUi,  149. 
Coal,  36 ;  structure  of,  163 ;  mode  of  for- 
mation of,  162. 
Coal-measures,  159,  160;    mineral   ohir- 

acters  of,   159;  mode  of  formation  of, 

160.  162 ;  plants  of,  162-170. 
Coccoliths,  261. 
Coccosteus,  151,  152. 
Cochliodus,  188;  contortus,  189. 
Coleoptera,  182,  311. 
ColossQchelys  A  tlas,  313. 
Columnaria,  105  ;  alveolata,  105. 
Coinatula,  232,  266. 


Conclusions  to  be  drawn  from  Fossils, 
52-56. 

Concretions,  calcareous,  29;  phosphatic, 
31  ;  of  clay-ironstone,  31 ;  of  luangauese, 
31. 

Conglomerate,  18. 

ConiferoK,  262 ;  wood  of,  13  ;  of  Devonian 
period,  138;  of  the  Carbouifeious,  17»; 
of  the  Permian,  196 ;  of  the  Trias,  208  ; 
of  the  Jurassic  period,  230. 

Coniston  Flags  and  Grits,  116. 

Connecticut  Sandstones,  footprints  of, 
222,  346. 

Conocoryphe  Mathewi,  85 ;  Sultzeri,  85. 

Conodonts,  114,  131. 

Constellaria,  105. 

Constricting  serpents  of  the  Eocene,  296. 

Contemporaneity  of  strata,  44-46. 

Continuity,  theory  of,  6-7. 

Conularia,  111,  129,  148,  186,  199,  237; 
ornata,  149. 

Conulus,  186. 

Conwi,  293. 

Coomhola  Grits,  158,  159. 

Coprolites,  31,  243. 

Coralline  Crag,  324. 

Corallines,  25. 

Corallium,  311. 

Coral-rag,  227,  229,  230. 

Coral-reefs,  24-26. 

Coral-rock,  26. 

Coral-sand,  19,  26. 

Corals,  103 ;  of  the  Lower  Silurian,  104, 
105  ;  of  the  Upper  Silurian,  119  ;  of  the 
Devonian,  140-143 ;  of  the  Carbonifer- 
ous. 172-175;  of  the  Permian,  197;  of 
the  Trias,  209  ;  of  the  Jurassic,  230,  231 ; 
of  the  Cretaceous,  266 ;  of  the  Eocene, 
292;  of  the  Miocene,  311. 

Corbula,  235. 

Cornbrash,  227,  229. 

Corniferous  Limestone,  135,  137. 

Cornulites,  123. 

Cornus,  262. 

Coryphodon,  300. 

Cowries,  259,  271,  293. 

Crabs,  180,  197,  233,  267. 

Crag,  Red,  324;  White,  324;  Norwich, 
324  ;  Antwerp,  325 ;  Bridlington,  325  ; 
Coralline,  324. 

Crania,  110,  127, 198,  269  ;  Ignabergensis, 
269. 

Crassatella,  292. 

Crepidophyllmn,  142;  Archiaci,  142. 

Cretaceous  period.  256-283 ;  rocks  of,  in 
Britain,  257-259;  in  North  America, 
260,  261 ;  life  of,  261-283. 

Crinoidal  Limestone,  24,  25. 

Crinoidea,  120 ;  of  the  Cambrian,  82 ;  of 
the  Low.ex  Silurian,  105 ;  of  the  Upper 
Silurian,  120-1-22 ;  of  the  Devonian,  143 ; 
of  the  Carboniferous.  175 ;  of  the  Per- 
mian, 197;  of  the  Trias,  209;  of  the 
Jurassic,  231;  of  the  Cretaceous,  266; 
of  the  Eocene,  292. 

Crioceras,  273 ;  cristatum.  274. 

Crocodilia,  218;  of  the  Trias,  21S;  of  the 
Jurassic,  251 ;  of  the  Cretaceous,  280 ; 
of  the  Eocene,  296,  297. 

Cromer  Forest-bed,  336. 

Crossozamites,  230. 

Crotalocrinus,  122. 


INDEX 


399 


Crustacea,  of  the  Cambrian,  83-87 ;  of  the 
Lower  Silurian,  Iu7,  loS;  of  the  Upper 
Silurian,  123-125;  of  the  Devonian,  144, 
145;  of  the  Carboniferous,  178-181;  of 
the  Permian,  197  ;  of  the  Trias,  210 ;  of 
the  Jurassic,  233 ;  of  the  Cretaceous, 
2rt7. 

Cryptogams,  164,  262. 

Ctenacanthus,  188. 

Ctenodonta,  111. 

Cupressus,  262. 

Cursores,  297,  346. 

Cuttle-fishes  (see  Dibranchiate  Cephalo- 
pods). 

Cyathocrinus,  175. 

Cyathophyllum,  119, 142, 173. 

Cycadopteris,  262. 

Cycads,  208;  of  the  Carboniferous,  170; 
of  the  Permian,  197;  of  the  Trias,  2"S ; 
of  the  Jurassic,  230;  of  the  Cretaceous, 
261. 

Cyclas,  268. 

Cyclonetna,  129. 

Cyclophthalmus  senior,  181. 

Cyclostoma,  294  ;  Arnoudii,  294. 

Cynodraco,  220. 

Cyprcea,  271,  293 ;  elegans,  393. 

Cypress,  262,  308,  311. 

Cypridina,  145. 

Cypridina  Slates,  145. 

Cyrena,  235,  268,  292. 

Cyrtina,  213,  214. 

Cyrtoceras,  114. 

Cystiphyllum,  119,  142,  173;  vcsiculosum , 
141. 

Cystoidea,  105-107;  of  the  Cambrian,  82; 
of  the  Lower  Silurian,  106;  of  the 
Upper  Silurian,  120. 

Dachstein  Beds,  205,  206 

Dadoxylon,  138,  170. 

Daonella,  211;  Lommelli,  211. 

Dasornis  Londinensis,  297. 

Decapod  Crustaceans,  180. 

Deer,  317,  329,  354. 

Deinosauria,  248 ;  of  the  Trias,  221 ;  of 
the  Jurassic,  248-251 ;  of  the  Cretaceous, 
277-279. 

Deinotherium,  319,  320 ;  giganteum,  320. 

Denbighshire  Flags  and  Giits,  115. 

Dendrocrinus,  82. 

Dendrograptus,  100. 

Desmids,  138,  261. 

Devonian  Formation.  133-136;  origin  of 
name,  133;  relation  to  Old  Red  Sand- 
stone, 133,  134 ;  of  Devonshire,  134 ; 
of  North  America,  135,  136;  life  of, 
136-156. 

Diadema,  266. 

Diatoms,  33;  of  the  Devonian,  138;  of 
the  Carboniferous,  104;  «.f  flints,  261; 
of  Richmond  Earth,  33,  307. 

Dibranchiate  Cephalopods,  112;  of  the 
Trias,  212 ;  of  the  Jurassic,  239-241 ; 
of  the  Cretaceous,  274.  275;  of  the 
Eocene,  294  ;  of  the  Miocene.  312. 

Diceras,  236;  arietina,  236. 

Diceras  Limestone,  227,  236. 

Dichobune,  303. 

Dichograptm,  101 ;  octobrachiatm,  101. 

Dicotyledonous  plants,  262. 

Dicotyles  antiqvus,  317. 

Dicranograpfus,  101,  119. 


D!ctt/onema.  89,  100,  119:  sociale,  89. 
Dicynodon,  220  ;  lacerticeps,  221. 
Didelphys,  254,  315;  gypaorum,  299. 
Didus  ineptus,  348. 

Didymograptus,  101 ;  divaricatus,  102. 
Difcellocephalm   Celticus,    84;    Minneso- 

tensis,  84. 
Dimorphodon,  247. 
Dinichthya,  153  ;  Hertzeri,  151. 
Dinoceras,  303 ;  mirabilis,  304. 
Dinocerata,  303,  3u4. 
Dmophis,  296. 
Dinornis,  346,  348;    elepkantopus,    34tf, 

347 ;  gigantetis.  346. 
Dinosauria  (see  Deinosauria). 
Dinotherium  (see  Deinotkerium). 
Diphyphyllum,  142. 
Diplograptiis,  101,  119;  prutis,  102. 
Dipnoi,  153,  187,  215. 
Diprotodon,  348,  349 ;  australis,  348. 
Diptera,  31]. 
Dlscina,  87,  110,  127,  198. 
Discnidea,  266  ;  cylindrica,  2fi7 
Dithyrocaris,  179  ;  Scouleri,  180. 
Dodo,  348. 
Dog  whelks,  293. 
Dolomite,  27,  28. 
Dolomitic  Conglomerate  of  Bristol,   201, 

219. 

Dolphins,  299,  315. 
Dorcatherium,  317. 
Dowtiton  Sandstone,  116. 
Draco  volans,  245. 
Dragon-flies,  311. 
Drift,  Glacial,  337. 
Dremotherium,  317. 
Drnmatherium  sylvestre,  223,  224 
Dryandra,  262. 
Dryopithecus,  323. 
Dugongs,  299. 

Echinoderrnata,  of  the  Cambrian,  82 ;  of 
the  Lower  Silurian,  105 ;  of  the  Upper 
Silurian,  120;  of  the  Devonian,  143  ;  of 
the  Carboniferous,  175  ;  of  the  Permian, 
197  ;  of  the  Trias,  209  ;  of  the  Jurassic, 
2.31;  of  the  Cretaceous,  266;  of  the 
Eocene,  292. 

Echinoidea,  177;  of  the  Upper  Silurian, 
120  ;  of  the  Devonian,  143  ;  of  the  Car- 
boniferous, 177  ;  of  the  Permian,  197 ; 
of  the  Jurassic,  233 ;  of  the  Cretaceous, 
266. 

Edentata,  349 ;  of  the  Eocene,  299  ;  of  the 
Miocene,  315;  of  the  Post-Pliocene, 
349-353. 

Edriocrinus,  122. 

Eifel  Limestone,  135 

Elasmobranchii  (see  Placcid  Fishes). 

Elasmosaurus,  276. 

Elephants,  319,  320,  330. 

Elephas,  320;  Americanus,  357;  anti- 
quus,  329,  330,  336,  341,  357  ;  Falconer i, 
359  ;  Melitensis,  359 ;  meridinnalis,  3'29, 
330,  336,  357  ;  plant  frons,  321  ;  primi- 
genius,  339,  341,  357,  358. 

Elk,  354  ;  Irish,  354,  355. 

Ellipsocephalus  Hoffi,  84. 

Elotherium,  317. 

Einydidce,  296. 

Emys,  280. 

Enaliosaiirinns.  219,  242,- 276. 

Encrinital  mar  Lie,  24. 


4OO 


INDEX. 


Encrinurui,  1 23. 

Encrinus  liliiformis,  209,  210. 

Endogenous  plants,  261. 

Endophyllum,  173. 

Sndothyra,  171 ;  Bailyi,  172. 

Engis  skull,  364. 

-Entomis,  145. 

Entomoconchus  Scouleri,  179,  180. 

Eocene  period,  284 ;  rocks  of,  in  Britain, 
287,  288 :  in  France,  288 ;  in  North 
America,  288,  289  ;  life  of,  289-305. 

E'icidaris,  197. 

.JSophyton,  80  ;  Linneanum,  81. 

E'tphyton  Sandstone,  79. 

Eosaurus  A  cadi  amis,  191. 

Eozoic  rocks,  <>7 

Eoznon  Bavaricum,  76. 

EoZ'jdn  Canadense,  68,  76 ;  appearance  of, 
in  mass,  69  ;  minute  structure  of,  70.  7 1 ; 
affinities  of,  with  Foraminifera,  71-74. 

Ephemeridce,  145,  183. 

Equisetacece,  166. 

Equisetites,  196. 

Equidce,  301,  302,  316,  328. 

Equus,  302  ;  caballvs,  354  ;  excelsus,  328 ; 
fossilis,  336,  354 

Eridophyllum,  142. 

Eryon  arctiformiv,  233,  234. 

Eschara,  267. 

Escharidce,  267. 

Excharina,  267  ;  Oceani,  268. 

Estheria,  145,  179,  210;  tenella,  180. 

Eucalyptocrinus,  122 ;  polydactylus,  122. 

Eucladia,  120. 

Euomphalus,  128.  148,  186,  199,  213;  dt«- 
cors,  129. 

Euplectella,  265. 

Euproops,  179. 

European  Bison,  3~<6. 

Eurypterida,  124,  179;  of  the  Upper  Silu- 
rian, 124;  of  the  Devonian,  144. 

Even-toed  Ungulates,  300,  317,  354. 

Exogenous  plants,  266. 

Exogyra,  236 ;  virgula,  236. 

Extinction  of  species,  57,  58. 

Fagus,  262. 

Faluns,  306. 

Fan-palrns,  308. 

Favistella,  105. 

Favosites,  119,  142;  Gothlandica,  143; 
hemisphcerica,  143. 

Faxoe  Limestone,  259,  286. 

Felis  angustus,  330  ;  Zeo,  361  ;  tspelcea,  361. 

Fenestella,  108,  125,  145,  184,  198.  210  ; 
cribrosa,  146;  magnified,  146  ;  retiformis, 
198. 

Fenestellidce,  183. 

Ferns,  of  the  Devonian,  136  ;  of  the  Car- 
boniferous, 164;  of  the  Permian,  196; 
of  the  Trias,  207  ;  of  the  Jurassic,  229  ; 
of  the  Cretaceous,  261. 

Fig-shells,  293. 

Fishes,  150;  of  the  Upper  Silurian,  13^, 
131;  of  the  Devonian,  150-155;  of  the 
Carboniferous,  187, 188  ;  of  the  Permian, 
199,  200  ;  of  the  Trias,  214,  215  ;  of  the 
Jurassic,  240-242  ;  of  the  Cretaceous,  275, 
276 ;  of  the  Eocene,  295,  296  ;  of  the 
Miocene,  312,  313. 

Flint,  33  ;  structure  of,  24;  oriein  of,  34  ; 
organisms  of,  84,  13S,  263;  of  Chalk,  34, 
259,  261. 


Hirnan  implements  associated  with  bones 
i>£  extinct  Mammals,  363,  S64. 

Flora  (see  Plants). 

Footprints  of  Cheirotherium,  215,  216 ; 
of  the  Triasaic  sandstones  of  Connecti- 
cut, 222. 

Foraminifera,  22-24,  71-74;  of  the  Cam- 
brian, 82;  of  the  Lower  Silurian,  98; 
of  the  Carboniferous,  171,  172;  of  the 
Permian,  197;  of  the  Trias,  209;  of  the 
Jurassic,  230;  of  the  Cretaceous,  VI, 
22,  263 ;  of  the  Eocene,  290 ;  of  the 
Miocene,  311  ;  of  the  Post-Pliocene, 
338  ;  of  Atlantic  ooze,  22,  2:5 ;  as  build- 
ers of  limestone,  24,  25,  28  ;  as  forming 
green  sands,  34. 

Forbesiocrimis,  175. 

Forest-bed  of  Cromer,  336. 

Forest-bugs,  311. 

Forest-marble,  227. 

Formation,  definition  of,  18 ;  succession 
of,  42. 

Fossiliferous  rocks,  14-37;  chronological 
succession  of,  37-44. 

Fossdisation,  processes  of,  11-14. 

Fossils,  definition  of,  11 ;  distinctive,  of 
rock-groups,  38;  conclusions  to  he 
drawn  from,  52-56;  biological  relations 
of,  57-61. 

Foxes,  304. 

Fringe-filmed  Ganoids,  153. 

Fucoidal  Sandstone,  79,  80. 

Fucofds,  80,  97. 

Fuller's  Earth,  227,  229. 

Fusulina,  172  ;  cylindrica,  172. 

Fusus,  237,  293. 

Galeocerdo,  312. 

Galei-ites,  266  ;  albo-galems,  267. 

Gaieties,  254. 

Ganoid  Fishes,  150  ;  of  the  Upper  Silurian, 
130 ;  of  the  Devonian,  150-153 ;  of  the 
Carboniferous,  187. 188;  of  the  Permian, 
199;  of  the  Trias,  214;  of  the  Jurassic, 
241 ;  of  the  Cretaceous,  275 ;  of  the 
Eocene,  295. 

Gaspe  Beds,  134. 

Gasteropoda,  of  the  Cambrian,  88  ;  of  the 
Lower  Silurian,  111;  of  the  Upper  Silu- 
rian, 128,  129 ;  of  the  Devonian,  148  ;  of 
the  Carboniferous,  186;  of  the  Permian, 
199;  of  the  Trias,  213  ;  of  the  Jurassic, 
236,  237  ;  of  the  Cretaceous,  271 ;  of  the 
Eocene,  292,  293. 

Gastornis  Parisiensis,  297. 

Gault,  257,  258. 

Gavial,  251,  297. 

Genesee  Slates,  135. 

Geological  record,  breaks  in  the,  47-52. 

Giraffes,  317. 

Glacial  period,  335  ;  deposits  of,  337,  338. 

Glanduliiw.,  311. 

Glauconite,  34,  74,  9S,  263. 

Glavconome,  126,  184  ;  pulcherritna,  183. 

Globe  Crinoids  (see  Cystoidea). 

Globigerina,  22,  23,  264. 

Glutton,  360. 

Glyptaster,  120. 

Glyptocrinus,  122. 

Gli/ptodon,  351,  352 ;  clavipef.  352. 

Glyptolcemus,  153. 

Goats,  318. 

Goniatitcs,  130,  149,  187,  214  ;  Jossce,  1S7. 


INDEX. 


4OI 


Gorgonidce,  292. 
iJraUatores.  297. 
Graphite,  36 ;  mode  of  occurrence  of,  36, 

68  ;  origin  of,  36. 
Graptolites,   89,   100 ;    structure  of,  100 ; 

of  the  Lower  Silurian,  Iu0-lu3;  of  the 

Upper  Silurian,  118.  119. 
Great  Oolite,  2<7,  2*9;   Upper,  257,  258, 

260 

Greenland,  Miocene  plants  of,  311. 
Greeusand,  Lower,  £57,  260. 
Green  sands,  origin  of,  44,  263. 
Grevillea,  262,  3u8. 
Gnfithides,  179. 
Grizzly  Bear,  359 
Ground  Sloths,  S51. 
Gryphcea,  236  ;  incurva,  236. 
Guelph  Limestone,  117. 
Gulo  luscus,  360  ;  spelceus,  360. 
Guttenstein  Beds,  205,  206. 
Gymnospermous  Exogens,  262. 
Gypsum,  32,  193,  204. 
Gyracanthus,  188. 
Gyroceras,  130. 

Hadrosaurus,  278. 

Haiitherium,  299. 

Hallstadt  Beds,  205,  206. 

Halobia,  211. 

Halysites,  119;  agglomerata,  120;  caten- 

ularia,  120. 

Hamilton  formation,  135,  137. 
Hamites,  273 ;  rotundus,  274. 
Haplophlebium  Barnesi,  182. 
Harlech  Grits,  78,  79. 
Harpesy  108,  123  ;  ungula,l24. 
Flastings  Sands.  257. 
Headon  and  Osborne  series,  287,  288. 
Heart-urchins,  311. 
Heliolites,  105,  119,  2fi6. 
Heliophyllvm,  142,  173 ;  exiguum,  141. 
Helix,  294. 
Helladotherium,  317. 
Heloporafragilis,  126. 
Hemicidaris  crenulam,  233. 
Hemiptera,  311. 
Hemitrochiscus  paradaxus,  197. 
Hempstead  Beds,  306. 
Hesperornis,  281,  282 ;  regalis,  282. 
Heteropoda,  111 ;  of  the  Lower  Silurian, 
111  ;  of  the  Upper  Silurian,  129  ;  of  the 
Devonian,  148;    of  the  Carboniferous, 
186. 

Hinnites,  213. 

Hipparion,  301,  3r2,  316,  317,  328. 
Hippopodium,  235 

Hippopotamus,  3(  2:  amphibhts,  317,  329; 
major,  329,  336,  354  ;  Sivalensis,  318. 

Hippothoa,  108. 

Hippurite  Marble,  270. 

Hippurites,  270;  Toucasiana,  271. 

Hipptiritidce,  270,  285. 

Hixtioderma,  82 

Hollow-horned  Ruminants,  317. 

Holocyatis  eleyans,  266. 

Holopea,  129  ;  subconica,  129. 

Holopella,  129,  213;  obaoleta,  129. 

Holoptychius,  153;  nobiJissimua,  154. 

Holostomatous  Univalves,  236,  293. 

Holothurians,  120. 

Holtenia,  264. 

Homacaiithus,  188. 


Homal<motu$,  123,  145 ;  arina'.ux,  144. 

Homo  diluvii  testis,  313. 

Honeycomb  Corals,  142 

Hoofed  Quadrupeds,  300. 

Hudson  River  Group,  95. 

Huronian  Period,  75,  76;  rocks  of.  75. 

Hycena  crocuta,  360;  spelcea,  360;  //ij>- 

parionum,  330. 
Hycenictis,  322. 
Hycenodon,  304. 
Hyalea  D'Orbignyana,  312. 
Hybodm.  214,  242,  275. 
Bydmctinia,  265. 
Hydroid  Zoophytes,  103,  2f  5. 
Hymenocaris  vermicauda,  84,  88. 
Hymenophyllites,  165. 
Hymenoptera,  311. 
Hyopotamns,  302. 
Hyperodapedon,  218. 
HypsiprymnopMs,  2'_'4. 
Hystrix  primigcnius,  322. 

Ichthyocrinus  Icevis.  122. 

Ichthyornis,  281,  2-^2:  dispar,  281,  282. 

Ichthyosaurus,  242,  243,  276;  communis, 
242. 

Ictitherium,  322 

Iguana,  277. 

Jguanodon,  277,  278  ;  Mantelli,  278. 

Ilfracombe  Group,  134. 

Illcemis,  108,  123 

Imperfection  of  the  palseontological  re- 
cord, 50,  51. 

Inferior  Oolite,  227,  229. 

Infusorial  Earth,  33. 

Inoceramus,  269  ;  sulcatus,  270. 

Insectivora,  of  the  Eocene,  3»5;  of  the 
Miocene,  322. 

Insects,  of  the  Devonian,  145 ;  of  the 
Carboniferous,  182 ;  of  the  Jurassic, 
233  ;  of  the  Miocene,  311,  312. 

Irish  Elk,  354,  355. 

Ischadites,  99,  118. 

Isopod  Crustaceans,  81. 

Jackson  Beds,  289 

Jurassic  peiiod,  226;  rocks  of,  226-229; 
life  of,  i  29-255. 

Kaidacarpum,  230. 
Kainozoic  period,  44,  284-287. 
Kangaroo,  348. 
Kelloway  Rock,  227 
Kent's  Cavern,  deposits  in,  343. 
Keuper,  204,  206. 
Kimmeridge  Clay,  227,  229. 
King-crabs,  84,  124,  125,  179. 
Koninckia,  213,  214 
Kossen  Beds,  205,  206. 

Labyrinthodon  Jcegeri,  217. 

Labyrinthodontia,  190 ;  of  the  Carbon- 
iferous, 189-191;  of  the  Permian,  2ou; 
of  the  Trias,  215-217. 

Lace-corals,  108,  125,  145,  183,  198,  210. 

Lacertilia,  202;  of  the  Permian,  201,  202; 
of  the  Trias,  217,  218  ;  of  the  Jurassic, 
251 ;  of  the  Cretaceous,  280. 

Lcelaps,  278. 

Lamellibranchiata,  of  the  Cambrian,  88 ; 
of  the  Lower  Silurian,  110;  of  the 
Upper  Silurian,  128 ;  of  the  Devonian, 


402 


INDEX. 


148;  of  the  Carboniferous,  186;  of  the 
Permian,  198  ;  of  the  Trias,  211 ;  of  the 
Jurassic,  234-236;  of  the  Cretaceous, 
268-270 ;  of  the  Eocene,  192. 

Lamna,  275,  312. 

Lamp-shells  (see  Brachiopoda). 

Land-tortoises,  313. 

Lauracece,  308. 

Laurentian  period,  65 ;  rocks  of,  65,  66 ; 
Lower  Laurentian,  66  ;  Upper  Lau- 
rentian, 66 ;  areas  occupied  by  Lau- 
rentian rocks,  66;  limestones  of,  66, 
67;  iron-ores  of,  68;  phosphate  of  lime 
of,  68 ;  graphite  of,  68  ;  life  of,  67-75. 

Leaf-beds  of  the  Isle  of  Mull,  306. 

Leda,  292  ;  truncata,  338. 

Leguminosites  Marcouanus,  263. 

Lemming,  344.  345. 

Lepadidce,  267. 

Lepadocrinws  Gebhardi.  1^6. 

Leperditia,  108;  canadvnsis,  107. 

Lepldaater,  120. 

Lepidechinus,  178. 

Lepidesthes,  178. 

Lepidodendroids,  166,  167,  2  7. 

Lepidodendron,  118,  136,  166,  196;  Stfrn- 
bergi,  167. 

Lepidoptera,  311. 

Lepidosiren,  153. 

Lepidosteus,  188. 

Lepidostrobita,  166. 

Lepidotus,  275. 

Leptcena,  lo9,  110,  125,  234;  Liamca, 
235;  sericea,  110. 

Leptoccelia,  127  ;  plano-convexa,  127. 

Lias,  226,  227,  229. 

Liohas,  108. 

Lierophycus  Ottawaensis,  97. 

Lignitic  Formatiou  of  North  America, 
288,  294. 

Lily-encrinite,  209,  210. 

Lima,  235. 

Lime,  phosphate  of,  30,  81 

Limestone,  23-27  ;  varieties  of,  27-30 : 
origin  of,  21 ;  microscopical  structure 
of,  26 ;  Crinoidal,  24 ;  Foraminiferal, 
24,  26;  coralline,  24;  magnesian,  27; 
metamorphic,  27 ;  oolitic,  28-30 ;  piso- 
litic,  29;  bituminous,  36;  Laurentian, 
67. 

Limncea,  294 ;  pyramidalis,  294. 

Limulus,  84,  124,  125,  179. 

Lingula,  87,  88,  110,  127,  147,  198;  Cred- 
nen,  198. 

Lingula  Flags,  77,  78,  79,  88. 

Lingulella,  87,  88;  Davisii,  88;  fernt- 
ginea,  88. 

Liriodendron,  262,  308 ;  MeeM,  263. 

Lithostrotion,  173;  irregular?,  174. 

Lituites,  130. 

Lizards  (see  Lacertilia). 

Llama,  354. 

Llanberis  Slates,  79. 

Llandeilo  rocks,  92,  94,  96 

Llandovery  rocks,  93 ;  Lower,  93  ;  Upper, 

Lobsters,  180,  210,  233,  267. 
Loess,  339. 

London  Clay,  287,  2S8 
Longmynd  rocks,  77-SO,  S3. 
Lonsdalna,  173. 
Lophiodon.  316. 
Lophopkytlum,  173. 


Lower  Cambrian,  77-79  ;  Chalk,  25"9  ;  Cre- 
taceous, 257,  258  ;  Devonian,  134  ; 
Eocene,  287,  288 ;  Greeusand,  257.  258 ; 
Helderberg,  117,  118;  Laurentian  rocks, 
66;  Ludlow  rock,  116;  Miocene,  305; 
Old  Red  Sandstone,  134 ;  Oolites,  227, 
229:  Silurian  period,  90-114;  rocks  of, 
in  Britain,  92-94;  in  North  America, 
94-96;  life  of,  97-114. 

Loxonetna,  186,  199,  213. 

Ludlow  rocks,  116,  117. 

Lycopodifice.ee,  118,  136,  167. 

Lynton  Group,  134. 

Lyrodetmm,  ill. 

Macaques,  323,  331. 

Afachceracanthux  major,  151,  155. 

Mar.hairodus,  221,  249,  322,  331,  360; 
cull  ride  us,  331 

Maclnrea,  111;  crenulata,  112. 

MacrHcheilm,  186,  li>9,  213 

Macropetalichthyx,  152;  Sullivanti,  151. 

Mact'otherium  giganteuin,  315. 

Macrurous  Crustaceans,  180. 

Maclra,  292. 

Maestricht  Chnlk,  259,  279,  286. 

Magnesian  Limestone,  27 ;  nature  and 
structure  of,  28;  of  the  Permian  series. 
194,  196. 

Magnolia.  262.  200.  3 in. 

Mammalia,  of  the  Trias,  223,  224;  of  the 
Jurassic,  253,  25»;  of  the  Eocene, 
299-305;  of  the  Miocene,  313-323;  of 
the  Pliocene,  327-331;  of  the  Post- 
Pliocene,  348-362. 

Mammoth,  339.  341,  344.  357-359. 

Man,  remains  of,  in  Post-Pliocene  de- 
posits, 341,  344. 

Manatee,  299. 

Mantellia,  230 ;  megalophylla,  230. 

Maple,  290,  308,  310 

Marble,  28;  encrinitil,  24;  statuary,  27. 

Marcellus  Shales,  135. 

Mariacnnus,  122. 

Marmots,  322. 

Marsupials,  299 ;  of  the  Trias.  223 ;  of  the 
Jurassic.  253,  254;  of  tlie  Eocene,  2P9; 
of  the  Miocene,  315  ;  of  the  Post-Plio- 
cene, 348,  319. 

Marsupiocrinus,  122. 

Marmpites,  266. 

Mastodon,  319,  321,  322;  Americanus, 
angustidens,  322;  Arvenensi-g,  329; 
lungirostris,  322 ;  Ohioticus,  357  ;  Siva- 
lensis,  321. 

Medina  Sandstone,  116. 

Megalichthys,  188. 

Megalodon,  148. 

Megalomits,  128. 

Megalonyx,  351. 

Megalosaurus,  249,  278. 

Megatherium,  35o,  351 ;  Cuvieri,  350. 

Melania,  294. 

Melonites,  178. 

Menevian  Group,  77-79. 

Menobranchus,  189. 

Meristella,  127;  cylindrica,  127;  inter- 
media, 127 ;  naviformis,  127. 

Mesopithecns,  323. 

Mesozoic  Period,  44. 

Michelima,  142. 

Micraster,  266. 

Microles'ea,  224 ;  antiq^tus,  223. 


INDEX. 


403 


Middle  Devonian,  134 ;  Eocene,  287,  288, 
289 ;  Oolites,  227 ;  Silurian,  91. 

Miliolite  Limestone,  290. 

Millepora,  230. 

Millstone  Grit,  159,  161. 

Miocene  period,  305  ;  rocks  of,  in  Britain, 
305,  306;  in  France,  306;  in  Belgium, 
307;  in  Switzerland,  30(5;  in  Austria, 
307 ;  in  Germany,  307  ;  in  Italy,  307 ;  in 
India,  307;  in  North  America,  3u7;  life 
of,  308-323. 

Mitre-shells,  271,  293. 

Mitra,  271,  293. 

Aloas  of  New  Zealand,  346  348. 

M  idiolopsis,  111  ;  Solvensts,  88. 

Molasse,  306. 

Mole,  322,  336. 

Monkeys,  305,  331. 

Monocotyledouous  plants,  202. 

Monograptus,  100,  119;  priodon,  119. 

Monotis,  211. 

Monte  Bolea,  fishes  of,  295. 

Montlivaltia,  209. 

Mosasauroids,  279,  280. 

Mosasaurus,  279;  Ctimpert,  279;  prin- 
ceps,  279. 

Mountain  Limestone,  158,  161. 

Mud-fishes,  153,  215. 

Mud-turtles,  280. 

Mull,  Miocene  strata  of,  3^6. 

Murchisonia,  111,  129,  19.J,  213;  gmcilis, 
111. 

Murex,  237,  293. 

Muschelkalk,  203,  204,  206. 

Musk-deer,  317. 

Musk-ox,  344,  345,  356. 

Musk-sheep,  356. 

Myliobatis  Edwardsii,  296. 

Mylodon,  351  ;  rdbustus,  352. 

Mycphona,  211;  lineata,  211. 

Myriapoda  of  the  Coal,  181,  182 

Nassa,  293. 

Natatores,  297. 

Natica,  271,  293. 

Nautilus,  112-114,  130,  149,  186,  199,  237, 

272,  294 ;  Danicus,  272  ;  pompilms,  237. 
Neanderthal  skull,  364. 
Neocomian  series,  257,  260. 
Neolimulus,  125. 

Nerincea,  237,  271 ;  GoodhetlL'i.,  •::  7. 
Merita,  393. 
Ifeuroptera,  311. 
Neuroptens,  136,  165   196. 
Newer  Pliocene,  323,  324. 
New  Red  Sandstone,  193,  203 
Newts,  189,  200,  217. 
Niagara  Limestone,  117. 
Xipadites,  290 ;  ellipticus,  290. 
A ceygerathia,  197. 
Norwich  Crag,  324. 
Nothoscturus,  219;  mirabilis,  21'J. 
Notidanus,  241. 
NuiYienius  gypsorum,  297. 
Nummuhna,    172,    290;     Icevijata,  29  > ; 

pristina,  172. 
Nummulitic  Limestone,  24,  287,  291. 

Oak,  262,  310. 

Obolella,  87  ;  sagittalis,  88. 

Odd-toed  Ungulates,  300,  315,  327,  353. 

Odontaspis,  275. 

Odontopterts,  1(55  ;  Schlotfieimi,  164. 


Odontopteryx,  297  ;  toliapicus,  297,  298. 

Odontor  nit  ties,  282. 

Ogyyia,  108  ;  Buchii,  107. 

O'lder  Pliocene,  323,  324. 

Oldhamia,  81 ;  antiqua,  82 ;  slates  of 
Ireland,  79,  80. 

Old  Red  Sandstone,  133  ;  origin  of  name, 
133;  of  Scotland,  134;  relations  of,  to 
Devonian,  133,  134,  155. 

Olenus,  108;  micrurus,  88. 

Oligocene,  305. 

Oltgoporus,  178. 

Olive-shells,  293. 

Omphyma,  119. 

Onchus,  130  :  temiistriatus,  131. 

Oneida  Conglomerate,  116. 

Onychoduz,  153  ;  wjmmdes,  151. 

Oolitic  limestone,  structure  of,  28  ;  mode 
of  formation  of,  30. 

Oolitic  rocks  (nee  Jurassic). 

Ooze,  Atlantic,  22,  33. 

Ophidia,  251 ;  of  the  Eocene,  296. 

Ophiuroidea,  of  the  Lower  Silurian,  105  ; 
of  the  Upper  Silurian,  120  ;  of  the  Car- 
boniferous, 177  ;  of  the  Trias,  210 ;  of 
the  Jurassic,  233. 

Opossum,  299,  315. 

Orbitoides,  291. 

Oriskany  Sandstone,  135. 

Onnoxylon,  138. 

Orohippus,  302. 

Orthis,  38, 109, 125,  147.  184, 199  ;  bifora'a. 
109  ;  Davidsoni,  127  ;  eleganiula,  127  ; 
ftabellulum,  109;  Hicksii,  38;  lenticu- 
laris,  38;  pi  catella.  110;  rempina'a, 
185 ;  subquadrata,  109  ;  testudinaria, 
110. 

Orthoceras,  89.  112,  113,  13%  149,  186, 
213  ;  c re bri septum,  113. 

Orthonota,  111. 

Orthoptera,  182.  311. 

Osmeroides,  276  ;  Muntelli,  276. 

Osmerus,  276. 

Osteolepis,  153. 

Ostracode  Crustaceans  of  the  Cambrian, 
83 ;  of  the  Lower  Silurian,  107 ;  of  the 
Upper  Silurian,  123;  of  the  Devonian, 
145;  of  the  Carboniferous,  179  ;  of  the 
Permian,  197 ;  of  the  Trias,  210 ;  of  the 
Jurassic,  233  ;  of  the  Cretaceous,  267. 

Ostrea  acuminata,  235  ;  Couloni,  269  ; 
deltoidea,  235 ;  distorta,  235  ;  expansa, 
greyarea,  235  ;  Marshii,  235,  236. 

Otodus,  295  ;  obliquus,  296. 

O'ozamites,  230. 

Otozoum,  206. 

Oudenodon,  220 ;  Bainii,  221. 

Ovibos  moschatus,  356. 

Oxford  Clay,  227,  229. 

Oxyrhina,  312  ;  xiphodon,  313. 

Oysters,  235,  236,  269. 

Pachyphyllum,  173. 

Palcearca,  111. 

Palceaster.  120  ;  Ruthveni,  121. 

Palaaterina,  120;  priinceoa,  121. 

Palcechmus,  120,  178  ;  ellipticus,  177. 

Palceocaris,  ISO  ;  typus,  180. 

Palceocoma,  120 ;  Colvini,  121. 

Palceocoryne,  172. 

Palaeolithic  man,  remains  of,  363-365. 

Palceomanon,  118. 

Palceoniscus,  188,  200. 


404 


INDEX. 


Palceontina  Oolitica,  233. 
Palaeontological  evideuce  as  to  Evolution, 

60,  372-374. 
Palseontological   record,  iiiirerfection    of 

the,  50,  51. 

Palaeontology,  definition  of,  10. 
PaUeonycti*,  304 
Palceop'his,  296  ;  toliapicus,  293 ;  typh&ux, 

296. 

Palceoreas,  318. 
Palceosaurm,   200,  218,  219 ;  platyodon, 

219. 

Palceosiren  Beinerti,  200. 
Pafa-otheriuin,  300  ;  magnum,  301. 
Palceoxylon,  170. 
Palaeozoic  period,  44. 
Palms,  230,  263,  290,  309,  309 
Paludina,  257,  294. 
Pandanece,  230. 
Pandanus,  262. 

Paradoxides,  86,  87,  108  ;  Bohemicus,  85. 
Parasmilia,  266. 
Parkeria,  264. 
Pear  Encrinite,  231. 
Pearly  Nautilus,  58,  111,  112,  237. 
Peccaries,  317. 
Pecopteris,  136,  165,  196. 
Pecten  Grcenlandicus,  338  ;  Island icits, 

338  ;  Valoniensis,  211,  212,  204. 
Penarth  Beds,  204. 
rennatulidce,  292. 
Pentacrinus,  231  ;    caput-meduscf,   231  ; 

fasciculosus,  232. 
Pentamerus,    125,    126;    galeatus,    126; 

Knightii,  128. 

Pentremites  (see  Blastoidea). 
Pentremites  eonuideus,  176;  pyrifonni*, 

176. 

Perching  Birds,  297. 
Percidce,  276. 
Periechocrinus,  122. 
Perissodactyle  Ungulates,  300,  315,  327. 
Permian    period,     192-202;     rocks  of,  in 
Britain,  194;    in  North  America,  194; 
life  of,  195-302. 

Persistent  types  of  life,  53,  371. 
Petalodus,  i88. 
Petraster,  120. 
Petroleum,  origin  of,  36. 
Pezopbaps,  348. 

Phacops,  108,  123,  145  ;  Doivningice,  124  ; 
granulatus,  144  ;  Icevis,  144  ;  latifrons, 
144,  145;  longicaudatus,  124;  ra««,  145. 
Phcenopora  enaifurmis,  126. 
Phalangers,  348. 
Phanerogams,  164. 
Phaneropleuron,  153. 
Phascolotherium,  253,  254. 
Pheronema,  264. 
Phillipsastrcea,  142. 
Phiilipsia,  179  ;  seminifera,  ISO. 
Pholadomya,  235. 
Pkormosoma,  178. 
Phorus,  271. 

Phosphate  of  lime,    concretions  of,   30  ; 
disseminated  in  rocks,  30  ;  origin  of,  31. 
Phyllograptus,  102;  «?//ms,  102. 
Phyllopoda,  of  the  Cambrian,  83 ;  of  the 
Lower  Silurian,  108  ;  of  the  Upper  Silu- 
rian, 123;  of  the  Devonian,  145  :  of  the 
Carboniferous,   179;    of   the    Permian, 
197  ;  of  the  Trias,  210. 


Phyllopora,  21  o. 

Pliysa,  294  ;  coltunnrtrix,  204. 

Pigs,  3i)2,  317,  329,  3;>4 

Pilton  Group,  lio. 

Pinites,  170 

Pisces  (see  Fishes). 

Pisolite,  29. 

Pisolitic  Limestone  of  France,  259,  286. 

Plaeudus,  220  ;  gigas,  220. 

Placoid  Fishes,  150;  of  the  Upper  Silurian, 
130,  131;  of  the  Devonian,  153-155;  of 
the  Carboniferous,  188;  of  the  Permian, 
199  ;  of  the  Trias,  214  ;  of  the  Jurassic, 
241;  of  the  Cretaceous,  275;  of  the 
Eocene,  295  ;  of  the  Miocene,  312. 

Plagiaulax,  254. 

Planohtes.  122  ;  vulgar  is,  123. 

Planorbis,  294. 

Plants,  of  the  Cambrian,  80,  81  ;  of  the 
Lower  Silurian,  97,  98;  of  the  Upper 
Silurian,  118;  of  the  Devonian,  136-139  ; 
of  the  Carboniferous,  163-170;  of  the 
Permian,  196;  of  the  Trias,  207,  208; 
of  the  Jurassic,  2-9,  230 ;  of  the  Cre- 
taceous, 261-263  ;  of  the  Eocene,  289, 
290;  of  the  Miocene,  308-311. 

Plamnopora,  119. 

Platanus,  262,  3  8  ;  aceroides,  309. 

Platephemera  anliqua,  145. 

Platyceras,  128,  148;  dumvsum,  148; 
multisinuatr.m ,  129  ;  ventricosuin,  1'29. 

Platycrinus,  122,  175;  tricontadactylux, 
J.75. 

Platyostoma,  129 ;  Xiagarense,  129. 

Platyrhine  Monkeys,  362. 

Platyschisma  helicites,  129. 

Platysomus,  200 ;  gibbosus,  199. 

Platystoma,  213. 

Pleistocene  period,  334  ;  climate  of,  3fi2. 

Plesipsaurus,  219,  243  245,  270;  dolicho- 
deirus,  244. 

Pleurocystiies  squamosus,  106. 

Pleurotoma,  293. 

Pleurotomaria,  111,  129,  186,  199,  236,  271. 

Plicatula,  213. 

Pliocene  period,  323 ;  rocks  of,  in  Britain, 
324;  in  Belgium,  325;  in  Italy,  325; 
in  North  America,  326;  life  of,  326-331. 

Pliopithecus,  322 ;  antiquus,  323. 

Pliosaurus,  245. 

Podocarya,  230. 

Podozamites,  208 ;  Innceolatus,  209. 

Polir-schiefer,  33. 

Polycystina,  32;  of  Barbmloes-earth,  33. 

Polypora,  145,  184 ;  dendroidea,  183. 

Polypterus,  153,  188. 

Polystomella,  311. 

Polytremacis,  266. 

Polyzoa,  of  the  Cambrian,  81,  89 ;  of  the 
Lower  Silurian,  10S ;  of  the  Upper 
Silurian,  125;  of  the  Devonian,  145, 
146;  of  the  Carboniferous,  183,  184; 
of  the  Permian,  198  ;  of  the  Trias,  210  ; 
of  the  Cretaceous,  267  ;  of  the  Miocene, 
312. 

Populus,  262. 

Porcellia,  186. 

Porcupines,  322. 

Portage  Group,  135. 

Port-Jackson  Shark,  154,  188,  24'2. 

Portland  beds,  227,  229. 

Post-Glacial  deposits,  3^6,  33S. 


INDEX. 


405 


Post-Pliocene  period,  334. 

Post-Tertiary  period,  286. 

Potenocrinus,  175. 

Potsdam  Sandstone,  79. 

Pie-Glacial  deposit*,  336. 

Prestwichfa,  179;  rotundata,  179. 

Primitia,  107;  strangulata,  107. 

Primordial  Trilobites,  85. 

Primordial  zone,  79. 

Proboscidea,  of  the  Miocene,  319,  322;  of 
the  Pliocene,  329,  330;  of  the  Post- 
Pliocene,  357-359. 

Producta,  147,  184,  198;  horrida,  IPS; 
longispina,  185;  semireticulata,  185. 

Productella,  147,  184. 

Productidw,  147,  211. 

Proetus,  123. 

Prong-buck,  318. 

Protaster,  120;  Sedpwickii,  121. 

Proteacece,  262,  308,  309. 

Proteus,  189. 

ProtichnUes,  87. 

Protocystites,  82. 

Protornis  Glarisiensis,  297. 

Protorosaurus,  201,  202  ;  Speneri,  201. 

Protospongia,  81 ;  fenestrata,  88. 

Prototaxites,  J18,  138;  Logani,  139. 

Psammobia,  292. 

Pmmmodus,  188. 

Psaronius,  136,  Ifi4. 

Pseudocrinus  bifasciatus,  106. 

Pailnphyton,  118,  137,  138  ;  princeps,  138. 

Pteranodon,  247.  277;  longiceps,  277. 

Pteraspis,  130,  152 ;  Banksii,  130. 

Pterichthys,  152 ;  cornutus.  153. 

Ptermcea,  128;  subfalcata,  128. 

Pteroceras,  237,  271. 

Pterodactylus,  245,  277;  crawirostris,  246. 

Pterophyllum,  208,  230  ;  Jcegeri,  209. 

Pteropoda,  of  the  Cambrian,  88 ;  of  the 
Lower  Silurian,  111;  of  the  Upper 
Silurian,  129;  of  the  Devonian,  148; 
of  the  Carboniferous,  186 ;  of  the  Per- 
mian, 199;  of  the  Jurassic,  237. 

Pterosauria,  245 ;  of  the  Jurassic,  245-248 ; 
of  the  Cretaceous,  277. 

Pterygotus  Anglicus,  124,  125. 

Ptilodictya,  108,  125  :  aewta,  109;/afc£- 
f or  mis,  109;  raripora,  126;  Schafferi, 
109. 

Ptychoceras,  273 ;  Emericianum,  274. 

Ptychodus,  275. 

Pupa  vetusta,  18fi. 

Purheck  Beds,  228  ;  Mammals  of,  254. 

Purpuroidea.  237. 

Pjicnodus,  275. 

P'yrula,  293. 

Cvadrumana,  of  the  Eocene,  305;  of  the 
Miocene,  32'2,  323  ;  of  the  Pliocene,  331 ; 
of  the  Post-Pliocene,  361. 

Quadrupeds  (see  Mammalia). 

Quaternary  period,  334. 

Quebec  Group,  95,  96,  101. 

Quercus,  262. 

Babbits,  322. 
Ttawa,  313. 
Raptores,  297. 
Rasores,  297. 
Recent  period,  286,  334. 
Receptaculites,  99. 


Red  clays,  origin  of,  35. 

Red  Coral,  311. 

Red  Crag,  324. 

Red  Deer,  336,  354. 

Reindeer,  344,  345,  354,  355. 

Remopleurides,  188. 

Reptiles,  200;  of  the  Permian,  200-202; 
of  the  Trias,  217-221;  of  the  Jurassic, 
242-251 ;  of  the  Cretaceous,  276-281 ;  of 
the  Eocene,  296,  297. 

Ret.epora,  108,  125,  145,  184,  198,  210; 
Ehrenbergi,  198 ;  Phillipsi,  146. 

Retiolites,  119. 

Retzia,  127. 

Rhsetic  Beds,  204-206. 

Rhamphorhynchus,  247;  Bitcklandi,  248. 

Rhinoceridce,  315. 

Rhinoceros  Etruscus,  327,  328,  336.  353; 
leptorhinus,  328;  megarhinus,  327-329, 
336,  353 ;  tichorhinus,  353,  354. 

Rhiiiopora  verrucosa,  126. 

Rhizodus,  188. 

Rhombus  minimus,  295. 

Rhyncholites,  239. 

Xhynchonella,  110,  127,  147,  184,  234,  268, 
292;  cuneata,  127;  neglecta,  127;  pleu- 
rodon,  185 ;  varians,  235. 

Rhynchosaurus,  218;  articeps,  218. 

Rice-shells,  293. 

Richmond  Earth,  33,  307. 

Ringed  Worms  (see  Annelida). 

River-gravels,  high-level  and  low-level, 
340,  341. 

Robulina,  311. 

Rocks,  definition  of.  14 ;  divisions  of, 
14,  15;  igneous,  14;  aqueous,  15-18; 
mechanically-formed,  18-20;  chemically- 
formed,  20;  organically-formed,  20-37; 
arenaceous,  20 ;  argillaceous,  20 ;  cal- 
careous, 20-32;  siliceous,  20,  32-34. 

Rodentia,  of  the  Eocene,  305 ;  of  the 
Miocene,  322 ;  of  the  Post-Pliocene,  361. 

Roebuck,  336,  354. 

Rostetlarta,  237,  293. 

Rotalia.  22,  98,  171,  2«4 ;  Boueana,  264. 

Rugose  Corals,  104;  of  the  Lower  Silurian, 
104,  105;  of  the  Upper  Silurian,  119; 
of  the  Devonian,  141  ;  of  the  Carbon- 
iferous, 172-174;  of  the  Permian,  197; 
of  the  Upper  Greensand,  266. 

Rupelian  Clay,  307. 

Sabal  major,  309. 

Sabre-toothed  Tiger,  322,  331. 

Saccammina,  172. 

Saccosoma,  232. 

Salamanders,  189,  313. 

Saliua  Group,  117. 

Salix,  262  ;  Meeki,  263. 

Salmonidce,  276. 

Sao  hirsuta,  85. 

Sassafras  cretacea,  263. 

Sauropterygia,  219. 

Scalaria,  271,  293;  Groenlandica,  338. 

Scaphites,  272,  273  ;  cnqualis,  274. 

Schizodus,  198,  211. 

Schoharie  Grit,  135,  137. 

Scolecoderma,  82. 

Scoliostoma,  213. 

Scolithus,  82 ;  Canadensix,  83. 

Scorpions  of  the  Coal-measures,  1S1. 

Scorpion-shells,  271. 


406 


INDEX. 


Screw-pines,  230. 

Scutella,  311;  nubratuada,  312. 

Sea-cows  (see  Sirenia). 

Sea-lilies  (see  Crinoidea). 

Sea-lizards  (see  Enaliosaurians). 

Seals,  322. 

Sea-mats  and  Sea-mosses  (xee  Polyzoa). 

Sea-shrubs  (see  Gorgonidtt). 

Sea-urchins  (see  Echir.oidea). 

Sea-weeds,  80,  81,  S3,  97,  136,  164,  261. 

Secondary  period.  44 

Sedimentary  rocks,  15. 

Semnopithecus,  322,  331. 

Septaria,  31. 

Sequoia,  306,  309,  310;  Couttxice,  309; 
gigantea,  309 ;  Langador/u,  309. 

Serolis,  84. 

Serpents  (see  Ophidia). 

Serpulites,  123. 

Sewalik  Hills  (see  Siwalik  Hills). 

Sheep,  355. 

Shell-sands,  19. 

Sigillaria,  168,  169 ;  Grceseri,  168. 

Sigillarioids,  136,  168,  170,  196. 

S'licates,  infiltration  of  the  shells  of  For- 
aminifera  by,  34,  74. 

Siliceous  rocks,  20,  32. 

Siliceous  Sponges,  265. 

Silicification,  13,  14. 

Silurian  period  (see  Lower  Silurian  and 
Upper  Silurian),  90-114  115-132. 

Simomurus,  219;  Gaillardoti,  219. 

Siphonia,  264  ;  ficus,  265. 

Siphonostomatous  Univalves,  237, 271,  '293. 

Siphnnotreta,  110. 

Sirenia,  299,  320 ;  of  the  Eocene,  299 ;  of 
the  Miocene,  315. 

Siren  lacertina,  200. 

Sivatherium,  318;  giganteum,  319. 

Siwalik  Hills,  Miocene  strata  of,  3u7. 

Skiddaw  Slates,  101. 

Sloths,  315,  349-351. 

Swilax,  308. 

Smithia,  173. 

Snakes  (see  Ophidia). 

Soft  Tortoises,  296. 

Solarium,  271. 

Solenhofen  Slates,  228. 

Solitaire,  346,  348. 

Spalacothertum,  254. 

Spatangus,  311. 

Sphierospongia,  139. 

Sphagodus,  130. 

Sphenodon,  218. 

Sphenoptens,  136,  165,  196. 

Spiders  of  the  Coal-measures,  181. 

Spider-shells,  237. 

Spindle-shells,  237. 

Spiri/era,  125,  147,  184,  19S,  2?4 ;  crispa, 
127;  disjuncta,  147;  hysteriea,  12<j; 
mucronata,  147;  Niagarensis,  127;  ros- 
trata,235;  sculptilis,\^i ;  trigonalis,\85. 

Spiriferidce,  147. 

Spirophyton  cauda-Galli,  135,  164. 

Spirorbis,  123,  143,  178  ;  A  rkonensis,  144  ; 
Carbonanus,  178;  laxus,  144;  Lewtsii, 
123  ;  omphalodes,  144  ;  spinultfera,  144. 

Spiruhrostra,  312. 

Spondylus,  269  :  spinosus,  270. 

Sponges,  of  the  Cambrian,  81  ;  of  the 
Lower  Silurian,  98  ;  of  the  Upper  Silu- 
rian, 119  ;  of  the  Devonian,  139  ;  of  the 


Carboniferous,  171  ;  of  the  Permian, 
197  ;  of  the  Trias,  2  .9  ;  of  the  Jurassic, 
230 ;  of  the  Cretaceous,  264,  265. 

Sponydla,  197. 

SponyUlopnis,  197. 

Sponyophylluin,  173. 

Spore-cases,  of  Cryptogams  in  the  Ludlow 
rocks,  118  ,  in  the  Coal,  163. 

Squirrels,  322. 

Stagonolepis,  218. 

Staircase-shells,  271. 

Stalactite,  21. 

Stalagmite,  21. 

Star- corals,  231. 

Star-fishes,  H-5,  120,  210. 

St  Cassian  Beds,  205,  206. 

Stephanophi/llia,  266. 

Stersognatkus,  253,  254. 

Stigmaria,  169;  ficoides,  Ifi9. 

Stouesfield  Slate,'  227 ;  Mammals  of,  253. 

Strata,  contemporaneity  of,  44. 

Stratified  rocks,  15-18. 

Streptelasma,  105. 

Streptorhynchus,  198. 

Stromatopora,  98,  99, 118, 139  ;  ntgosa,  99 ; 
tuberculata,  140. 

Strombodes,  119;  pentagomus,  104. 

Strombus,  271. 

Strophalosia,  198. 

Strophodux,  255. 

Strophomena,  109,  110,  125,  147,  181 ; 
altcmata,  110  ;  deltoidea,  109  ;  filitexta, 
110;  rhomboidalis,  147,  148;  subplana, 
127. 

Sul>  Apennine  Beds,  325. 

Sub-Carboniferous  rocks,  158,  161. 

Succession  of  life  upon  the  globe,  367-374. 

Suida,  302,  317,  329. 

Sulphate  of  lime,  22. 

Sus  Erymanthius,  317  ;  scrofa,  354. 

Synastrcva.  209. 

Syiihelia  Sharpeana,  266. 

Symcladia,  198 ;  virgulacea,  19S. 

Syringopora,  11»,  173  ;  raimilosa,  174. 

Tabulate  Corals,  104;  of  the  Lower  Silu- 
rian, 105  ;  of  the  Upper  Silurian,  119; 
of  the  Devonian,  142;  of  the  Carbon- 
iferous, 172;  of  the  Permian,  197. 

Talpa  Europcea,  336. 

Taplridce,  300. 

Tapirs,  300. 

Tapirus  Aroernensis,  327. 

Taxocrinus  tubercuiatus,  122. 

Taxodium,  262,  3u8,  310. 

Teleosaurus,  251. 

Teleostean  Fishes,  150;  of  the  Cretaceous, 
276. 

Telerpeton  Elginense,  218. 

Tellina  proximo,,  338 

Tent.aculites.  129,  148  ;  ornatus,  129. 

Terebra,  293^ 

Terebratella,  268  ;  Astieriana,  268. 

Terebratula,  184,  234;  digona,  235;  e.lon- 
gata,  168;  hastata,  185;  quadrifida, 
235  ;  sphcKroidalis,  235. 

Terebratulina,  268  ;  caput-serpentis,  268  ; 
striata,  268. 

Termites,  311. 

Terrapins,  280,  296. 

Tertiary  period,  44,  2S4-2S7. 

Tertiary  rocks,  classification  of,  284  287. 


INDEX. 


407 


Testudinidce,  313. 

Tetrabranchiate  Cephalopoda,  112;  of  the 
Cambrian,  89 ;  of  the  Lower  Silurian, 
112-114  ;  of  the  Upper  Silurian,  130;  of 
the  Devonian,  149  ;  of  the  Carboniferous, 
186,  187  ;  of  the  Permian,  199 ;  of  the 
Trias,  212;  of  the  Jurassic,  237-239;  of 
the  Cretaceous,  272-274  :  of  the  Eocene, 
294  ;  of  the  Miocene,  312. 

Textulana,  22,  2(54,  311  ;  Meyeriana,31I. 

Thanet  Sands,  287,  288. 

Theca,  88,  111,  129. 

Theca  Damdh,  88. 

Thecidium,  213. 

Thecodont  Reptiles,  218. 

Thecodontosaurus,  200, 218 ;  antiquus,  219. 

Thecosmihci  annularis,  231. 

Tkelodus,  131. 

Theriodotit  Reptiles,  202,  220. 

Thylacoleo,  349. 

Tile-stones,  11(5. 

Titanotherium,  316 

Toothed  Birds,  281-283. 

Tortoises,  202,  296. 

Tragoceras,  318. 

Travertine,  21. 

Tree-Ferns,  of  the  Devonian,  136;  of  the 
Coal-measures,  1(54. 

Tremadoc  Slates,  77-79. 

Trematis,  110. 

Trenton  Limestone,  95,  96. 

Trianthrm  Beckii,  107. 

Triassic  period,  203;  rocks  of,  in  Britain, 
204;  in  Germany,  204  ;  in  the  Austrian 
Alps,  205;  in  North  America,  205;  life 
of,  206-224. 

Triconodon,  254. 

Tngonia,  235,  255,  269. 

Trtgoniadce,  198,  211. 

Trigonocarpuin,  170  ;  ovatuin,  170. 

Trilobites,  84-87;  of  the  Cambrian,  85,  87; 
of  the  Lower  Silurian.  107,  108;  of  the 
Upper  Silurian,  123,  124  ,  of  tlie  De- 
vonian, 144,  145  ;  of  the  Carboniferous, 
179. 

Trimerellidce,  127. 

Trinucleus,  108  ;  concentricus,  107. 

Trionycidce,  296. 

Triton,  293 

Trochocyathw,  266. 

Trochonema,  129. 

Trogontherium,  361 ;  Cuvleri,  336,  361. 

Trumpet-shells,  293. 

Tulip-tree,  262,  308. 

Turbinolia  sulcata,  292. 

Turbinohdce,  292. 

Turrilites,  272,  273  :  catenulaius,  274. 

Turritella,  271,  293 

Turtles,  202,  251,  280,  296. 

Typhis  tubifer,  293. 

Ullmania  selaginoides,  197. 

Unconformability  of  strata,  48. 

Under-clay  of  coal,  162. 

Ungulata,  of  the  Eocene,  300-303  ;  of  the 
Miocene,  315-319  ;  of  the  Pliocene,  3^7- 
329  ;  of  the  Post-Pliocene,  353  357. 

Uniformity,  doctrine  of,  5-7. 

Unio,  250. 


Univalves  (see  Gasteropoda). 

Upper  Cambrian,  77  -  79  ;  Chalk,  2E>9  ; 
Cretaceous,  257,  260;  Devonian,  135; 
Eocene,  287,  288;  Greensand,  258; 
Helderberg,  135  ;  Laurentian,  66  ;  Llan- 
dovery,  115 ;  Ludlow  rock,  116 ;  Mio- 
cene, 305  ;  Oolites,  227  :  Silurian  period, 
115;  rocks  of,  in  Britain,  115,  116;  in 
North  America,  116-118  ;  life  of,  118-131. 

Uraus  nrctos,  359 ;  A  rverncnsis.  33  > ;  J'e- 
rox,  359  ;  spelcea,  360. 

Urm,  336,  356. 

Valley-gravels,    high-level  and  low-level, 

339-341. 

Vanessa  Pluto,  312. 
Varamdce,  202. 
Vegetation  (see  Plants). 
Ventriculites,  264,  265  ;  simplex,  265. 
Venus's  Flower-basket,  265. 
Vermilia,  197. 

Vespertiho  Parisiensis,  304,  305. 
Vicksburg  Beds,  289. 
Vines,  306,  309,  310. 
Vitreous  Sponges,  264. 
Voltzia,  208  ;  heterophylla,  209. 
Valuta,  271,  293  ;  elongala,  271. 
Volutes,  271,  2J>3,  312. 

Walchia,  196,  197 ;  piniformis.  196. 

Walrus,  322. 

Weal  den  Beds,  257. 

Wellingtons,  309,  310. 

Wenlock  Brds,  115,  117;  Limestone,  115; 

Shale,  115. 
Wentle-traps,  271. 
Werfen  Beds.  205,  2*6 
Whalebone  Whales,  299,  315 
Whales,  299,  315. 
Whelks,  237. 
White  Chalk,  259;  structure  of,  21,  22; 

origin  of,  23,  2(53. 
White  Crag,  324. 
White  River  Beds,  307. 
Wild  Boar.  354. 
Williarnsonia,  230. 
Winged  Lizards  (see  Pterosauria) 
Winged  Snails  (see  Pterupoda). 
Wing-shells,  271. 
Wolf,  336,  360. 
Wolverine,  360. 
Wombats,  348. 
Woolhope  Limestone,  115. 
Woolly  Rhinoceros,  339,  341,  344,  35?. 
Woolwich  and  Reading  Beds,  287. 
Worm -burrows,  82,  83,  123. 

Xanthidia,  138, 161. 
Xenoneura  antiquorum,  145. 
Xiphodon,  303. 
Xylobius,  182  ;  Sigillarice,  182 

Zamia  spiralis,  208. 

Zamites,  208,  230,  310. 

Zaphrentis,  105,  119,  142,  173;  cornicula, 

141;  StoJcesi,  104;  vermicular  is,  174. 
Zeacrinus,  175. 
Z^ehstein,  194. 
Zeuglodon,  299,  315  ;  cetoides,  299,  3  0. 


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